Near Tapachula, Mexico (CNN) Crowds of migrants resumed their long journey north on Sunday from the Mexican border city of Ciudad Hidalgo, according to Mexican federal police officers.

The caravan was headed for Tapachula, a city about 37 kilometers (23 miles) north of the Mexico-Guatemala border, the officers told CNN.

There were about 10 buses awaiting migrants along the highway between Tapachula and Ciudad Hidalgo and the drivers had been instructed to carry the migrants to shelters in Tapachula, the officers said. It was unclear how many of the group were from the migrant caravan and how many were Mexicans who joined the march.

One migrant, a 20-year-old Honduran named William, told CNN he crossed into Mexico via a float that carried him across the muddy Suchiate River on Saturday.

A 20-year-old named William said he left Honduras looking for work.

He left home looking for work, he said, and was ultimately bound for either Mexico or the United States, wherever he could land a job.

"There is no work back home," he said. "No future."

From Friday to Sunday, 1,028 people requested asylum in Mexico, Mexican authorities said Sunday. The government said 346 migrants in "vulnerable" conditions had been transferred to a shelter in the state of Chiapas.

In earlier statements, the government said authorities had given "priority attention" to elders, children and women -- some of whom were pregnant. It said there were 2,200 migrants remaining on the bridge connecting Guatemala and Mexico, and about 900 tried to cross into Mexico illegally.

The Honduran Foreign Ministry previously said 2,000 people in the caravan had turned around and headed home.

Thousands of Central American migrants fleeing poverty and violence were initially prevented from crossing the bridge.

On Friday, Mexican authorities began allowing a trickle of migrants, starting with women and children, to pass through the gates and board buses bound for refugee camps.

Caravan of migrants continues trip into Mexico, thousands of people. pic.twitter.com/VbZWFjxzQC — Patrick Oppmann CNN (@CNN_Oppmann) October 21, 2018

Others pushed through or climbed over a steel gate before riot police stopped them with tear gas and smoke canisters. Some migrants collapsed, coughing or weeping, according to video from the scene.

It's unclear exactly how many migrants were allowed to legally cross the border into Mexico, where they were taken to shelters to rest. On Saturday, with the punishing heat bearing down on them, some migrants took matters into their own hands, and crossed into Mexico on rafts that ferried them across the river.

We confirmed the Guatemala side is open if #CaravanaMigrantes wants to go back. But some are choosing to jump pic.twitter.com/DEvQSPoJoX — Bill Weir (@BillWeirCNN) October 20, 2018

One of the migrants marching to Ciudad Hidalgo, Luis Miguel Martinez, 30, also said his goal was to find work in the United States so he could feed his family, including two daughters he left behind in Honduras.

He was carrying a pink backpack and a blanket for a woman who also had a small child. But he was happy to help.

"We are one group," he said. "One people."

The crowd stretched all the way to the horizon. Some carried a Honduran flag, chanting "Mexico. Others hitched a ride, hanging off a tractor trailer headed for Tapachula.

Members of the migrant caravan walk into the interior of Mexico after crossing the Guatemalan border on October 21, 2018 near Ciudad Hidalgo, Mexico.

What happens next?

It's unclear whether the caravan will be allowed to reach the US border. Mexican authorities previously outlined their plan to respond to the caravan once it arrived at the Mexican border.

• Anyone with a valid visa will be able to enter and move freely.

• Anyone who wants to be recognized as a refugee or as a beneficiary of "complementary protection measures" must do so individually. Those who do so will be held "at a migratory station" for as many as 45 business days.

• Anyone who enters "in an irregular manner" will be "rescued and subject to an administrative procedure and, where appropriate, will be returned to their country of origin in a safe and orderly manner."

Photos: The caravan's journey, in photos Migrants heading in a caravan to the United States rest on a basketball court in San Pedro Tapanatepec, Mexico. on Sunday, October 28. Hide Caption 1 of 60 Photos: The caravan's journey, in photos Migrants rest on a road between the Mexican states of Chiapas and Oaxaca after federal police briefly blocked them outside the town of Arriaga on Saturday, October 27. Hide Caption 2 of 60 Photos: The caravan's journey, in photos The caravan comes to a standstill after police block it outside Arriaga on Saturday. Hide Caption 3 of 60 Photos: The caravan's journey, in photos Police in riot gear block the highway to stop a caravan of thousands of Central American migrants from advancing through Mexico on Saturday. Hide Caption 4 of 60 Photos: The caravan's journey, in photos Migrants travel on a cattle truck, as a thousands-strong caravan of Central American migrants slowly makes its way toward the US border, between Pijijiapan and Arriaga, Mexico, on Friday, October 26. Hide Caption 5 of 60 Photos: The caravan's journey, in photos Migrants heading in caravan to the United States rest on the train tracks in Arriaga, Mexico. Hide Caption 6 of 60 Photos: The caravan's journey, in photos A truck of migrants heads in a caravan to the United States. Defense Secretary James Mattis is expected to sign deployment orders that could send 800 or more US troops to the border. Hide Caption 7 of 60 Photos: The caravan's journey, in photos Jensi, a 14 year old migrant girl from Honduras, baths in a fresh water stream as she and others, part of caravan of thousands from Central America en route to the United States, take rest in Pijijiapan, Mexico on October 25. Hide Caption 8 of 60 Photos: The caravan's journey, in photos Central American migrants rest for the night in Pijijiapan, Mexico, on Thursday, October 25. Hide Caption 9 of 60 Photos: The caravan's journey, in photos Families rest on a roadside between Mapastepec and Huixtla, Mexico, while traveling with thousands of migrants from Central America in a caravan en route to the United States, on Wednesday, October 24. Hide Caption 10 of 60 Photos: The caravan's journey, in photos Migrants ride on the back of a truck heading to the US border from the outskirts of Tapachula, Mexico, on Monday, October 22. The majority of migrants made their way on foot. But some also flagged down cars and trucks passing by and piled onto any vehicle that would take them. Hide Caption 11 of 60 Photos: The caravan's journey, in photos Migrants take shelter from the weather under a tarp as they rest in the town of Huixtla, Mexico, on October 22. Hide Caption 12 of 60 Photos: The caravan's journey, in photos Migrants select clothes that have been placed along the road by Mexican citizens. Hide Caption 13 of 60 Photos: The caravan's journey, in photos Migrants rest in the town of Huixtla, Mexico. Hide Caption 14 of 60 Photos: The caravan's journey, in photos Migrant men bathe using water from a fire hydrant at the main plaza in Tapachula, Mexico. Hide Caption 15 of 60 Photos: The caravan's journey, in photos A migrant caravan headed to the United States walks into Mexico after crossing the Guatemalan border on Sunday, October 21. Hide Caption 16 of 60 Photos: The caravan's journey, in photos Central American migrants hitchhike along the highway near the border with Guatemala, as they continue their journey trying to reach the United States. Hide Caption 17 of 60 Photos: The caravan's journey, in photos A Mexican Federal Police helicopter flies over migrants heading in a caravan to the United States, on the road linking Ciudad Hidalgo and Tapachula in Mexico. Hide Caption 18 of 60 Photos: The caravan's journey, in photos Central American migrants walk north toward Tapachula after departing Ciudad Hidalgo, Mexico. Hide Caption 19 of 60 Photos: The caravan's journey, in photos Local residents cheer as a migrant caravan walks into the interior of Mexico after crossing the Guatemalan border. Hide Caption 20 of 60 Photos: The caravan's journey, in photos Migrants still on the Guatemalan side of the border sleep at a temporary immigrant shelter on Sunday in Ciudad Tecun Uman, Guatemala. The caravan of thousands of Central Americans made its way into Mexico with some members hoping to eventually reach the United States. Hide Caption 21 of 60 Photos: The caravan's journey, in photos Honduran migrants, part of a caravan heading toward the United States, travel on the road linking Ciudad Hidalgo and Tapachula, Chiapas state, Mexico, on Sunday. Hide Caption 22 of 60 Photos: The caravan's journey, in photos Central American migrants walking to the United States continue their journey, departing Ciudad Hidalgo, Mexico, on Sunday. Hide Caption 23 of 60 Photos: The caravan's journey, in photos A Honduran migrant boy, part of a caravan heading to the United States, walks on the road linking Ciudad Hidalgo and Tapachula, Chiapas state, Mexico, on Sunday. Hide Caption 24 of 60 Photos: The caravan's journey, in photos Honduran migrants who have already reached Mexican soil cheer at the rest of the group still waiting to cross at the Guatemala-Mexico border bridge in Ciudad Hidalgo, Mexico, on Saturday, October 20. Hide Caption 25 of 60 Photos: The caravan's journey, in photos Children of migrants, part of the caravan, on Saturday wait with their parents to apply for asylum in Mexico at a checkpoint in Ciudad Hidalgo, Mexico. Hide Caption 26 of 60 Photos: The caravan's journey, in photos A Honduran migrant mother and her son walk on the bridge after crossing the border between Guatemala and Mexico on Saturday. Hide Caption 27 of 60 Photos: The caravan's journey, in photos Mexican paramedics help a Honduran woman who fainted after crossing the border between Guatemala and Mexico on Saturday. Hide Caption 28 of 60 Photos: The caravan's journey, in photos Honduran migrants help some of their members get down to the Suchiate River from the Guatemala-Mexico border bridge in Ciudad Hidalgo on Saturday. Hide Caption 29 of 60 Photos: The caravan's journey, in photos A migrant is comforted by a Mexican paramedic after her mother fainted while crossing the border between Guatemala and Mexico. Hide Caption 30 of 60 Photos: The caravan's journey, in photos Honduran migrants from the caravan on Saturday cross the Suchiate River, a natural border between Guatemala and Mexico. Hide Caption 31 of 60 Photos: The caravan's journey, in photos A Honduran migrant looks through the gate on the bridge that connects Mexico and Guatemala in Tecun Uman, Guatemala, on Saturday. Hide Caption 32 of 60 Photos: The caravan's journey, in photos Migrants in the caravan wait on Saturday for the opening of the gate on the bridge that connects Guatemala to Mexico. Hide Caption 33 of 60 Photos: The caravan's journey, in photos Thousands of Honduran migrants rush across the border toward Mexico, in Tecun Uman, Guatemala, Friday, October 19. Hide Caption 34 of 60 Photos: The caravan's journey, in photos A Honduran man protects his child after fellow migrants, part of a caravan trying to reach the United States, stormed a border checkpoint in Guatemala, in Ciudad Hidalgo, Mexico, Friday, October 19. Hide Caption 35 of 60 Photos: The caravan's journey, in photos Honduran migrants, part of a caravan trying to reach the United States, storm a border checkpoint to cross into Mexico, in Tecun Uman, Guatemala, Friday, October 19. Hide Caption 36 of 60 Photos: The caravan's journey, in photos Mexican federal police officers allow women and children taking part in a caravan of Honduran migrants heading to the United States to cross to Mexico in the border city of Tecun Uman, Guatemala, on Friday, October 19. Hide Caption 37 of 60 Photos: The caravan's journey, in photos An aerial view shows a Honduran migrant caravan heading to the United States as it is stopped at a border barrier on the Guatemala-Mexico international bridge in Ciudad Hidalgo, Mexico, on Friday, October 19. Hide Caption 38 of 60 Photos: The caravan's journey, in photos Honduran migrants heading in a caravan to the United States remove a barrier at the Guatemala-Mexico border bridge in Ciudad Hidalgo, Mexico, on Friday, October 19. Hide Caption 39 of 60 Photos: The caravan's journey, in photos A child is lifted over the border fence as thousands of Honduran migrants rush across the border toward Mexico, in Tecun Uman, Guatemala, Friday, October 19. Hide Caption 40 of 60 Photos: The caravan's journey, in photos A Honduran migrant mother and child are surrounded by Mexican Federal Police in riot gear, at the border crossing in Ciudad Hidalgo, Mexico, Friday, October 19. Hide Caption 41 of 60 Photos: The caravan's journey, in photos A Honduran migrant, part of a caravan trying to reach the United States, storms the checkpoint between Guatemala and Mexico in Tecun Uman, Guatemala, Friday, October 19. Hide Caption 42 of 60 Photos: The caravan's journey, in photos Honduran migrants heading in a caravan to the United States rush through the Guatemala-Mexico border bridge after tearing down its gate in Ciudad Hidalgo, Mexico, on Friday, October 19. Hide Caption 43 of 60 Photos: The caravan's journey, in photos Honduran migrants heading in a caravan to the United States crowd the gate of the Guatemala-Mexico border bridge in Ciudad Hidalgo, Mexico, on Friday, October 19. Hide Caption 44 of 60 Photos: The caravan's journey, in photos Honduran migrants wait at the Mexican border in Tecun Uman, Guatemala, on Friday, October 19. Thousands of migrants traveling in a caravan briefly moved toward the border crossing between the two countries before turning around. Guatemala has closed its border gate and is standing guard with dozens of troops and two armored jeeps. Hide Caption 45 of 60 Photos: The caravan's journey, in photos Honduran migrants leave Guatemala City, Guatemala, at sunrise on Thursday, October 18, 2018, as they make their way north toward the United States. Many of the more than 2,000 Hondurans in a migrant caravan trying to wend its way to the United States left spontaneously with little more than the clothes on their backs and what they could quickly throw into backpacks. Hide Caption 46 of 60 Photos: The caravan's journey, in photos Migrants display the flag of Honduras while on a caravan of migrants en route to the Mexican border on Thursday in Guatemala City. The caravan of thousands of Central Americans, most from Honduras, hopes to eventually reach the United States. President Donald Trump has threatened to cancel the recent trade deal with Mexico and withhold aid to Central American countries if the caravan isn't stopped before reaching the United States. Hide Caption 47 of 60 Photos: The caravan's journey, in photos A Honduran migrant, part of a caravan trying to reach the United States, pushes a stroller with a boy during a new leg of their travel in Guatemala City on Thursday. Hide Caption 48 of 60 Photos: The caravan's journey, in photos Honduran migrants in the caravan are pictured inside a truck on Thursday. Hide Caption 49 of 60 Photos: The caravan's journey, in photos Honduran migrants hike in the forest after crossing the Lempa River, on the border between Honduras and Guatemala, to join the caravan on Thursday. Hide Caption 50 of 60 Photos: The caravan's journey, in photos Honduran migrants climb into the bed of a truck in Zacapa, Guatemala, on Wednesday, October 17, 2018. Hide Caption 51 of 60 Photos: The caravan's journey, in photos A Honduran migrant, part of the caravan, rests on a street as he looks through his mobile phone in Guatemala City on Wednesday. Hide Caption 52 of 60 Photos: The caravan's journey, in photos A child lies on the ground to rest as Honduran migrants take part in a caravan to the United States in Teculutan, Guatemala, on Wednesday. Hide Caption 53 of 60 Photos: The caravan's journey, in photos Honduran migrants heading to the United States rest at a gymnasium of a Catholic church in Chiquimula, Guatemala, on Tuesday, October 16, 2018. The caravan set out October 13 from the impoverished, violence-plagued country. Hide Caption 54 of 60 Photos: The caravan's journey, in photos Honduran migrants pray at an improvised shelter in Chiquimula, Guatemala, on Tuesday. Hide Caption 55 of 60 Photos: The caravan's journey, in photos Families in the caravan rest for the night in a community gym on Tuesday in Chiquimula, Guatemala. The caravan is the second of its size in 2018. Hide Caption 56 of 60 Photos: The caravan's journey, in photos Honduran migrants move north on Tuesday near Quezaltepeque, Guatemala. Hide Caption 57 of 60 Photos: The caravan's journey, in photos Honduran migrants holds up their national ID cards as Guatemalan police block them and their caravan after the group crossed the Honduras-Guatemala border in Esquipulas, Guatemala, on Monday, October 15, 2018. Police stopped the migrants for several hours but the travelers refused to return to the border and were eventually allowed to pass. Hide Caption 58 of 60 Photos: The caravan's journey, in photos The caravan moves north after crossing the border from Honduras into Guatemala on Monday. Hide Caption 59 of 60 Photos: The caravan's journey, in photos The caravan pauses at a Guatemalan police checkpoint after crossing the border from Honduras on Monday. Hide Caption 60 of 60

President tweets about caravan

Its slow procession north has prompted US President Donald Trump to threaten to cut aid to Central American nations and to send troops to the US border if Mexico fails to stop the surge.

"Full efforts are being made to stop the onslaught of illegal aliens from crossing our (southern) Border," Trump tweeted Sunday. "People have to apply for asylum in Mexico first, and if they fail to do that, the US will turn them away. The courts are asking the US to do things that are not doable!"

Full efforts are being made to stop the onslaught of illegal aliens from crossing our Souther Border. People have to apply for asylum in Mexico first, and if they fail to do that, the U.S. will turn them away. The courts are asking the U.S. to do things that are not doable! — Donald J. Trump (@realDonaldTrump) October 21, 2018

He followed that tweet with another : "The Caravans are a disgrace to the Democrat Party. Change the immigration laws NOW!"

The caravan formed just weeks before the US midterm elections. And many Republican candidates have echoed Trump's rhetoric about boosting border security and cracking down on illegal immigration.

The US President has pointed to the caravan as a key issue in the upcoming elections, and has used it to attack Democrats, saying -- without evidence -- they wanted the caravan to arrive before Election Day so the migrants would vote for Democrats.

But as asylum-seekers, the migrants would not be citizens and would not be allowed to vote.

US warning over exploitation

US Secretary of State Mike Pompeo reiterated that the United States would not allow illegal immigrants entry and said the the government was closely watching the caravan.

In a statement Sunday evening, Pompeo warned that "we are concerned that these migrants may be victimized by human smugglers or others who would exploit them. We also are deeply concerned by the violence provoked by some members of the group, as well as the apparent political motivation of some organizers of the caravan."

Homeland Security Secretary Kirstjen Nielsen earlier issued a separate statement saying "we must remain mindful" of criminals who try to prey on those participating as the caravan makes its way to Mexico. She said the United States will work with its partners to investigate and prosecute those who try to profit from it.