Central American migrants, travelling in a caravan from Honduras, tried to force their way through the Mexico-Guatemala border Monday after the Mexican government rejected their request to transit toward the United States.

About a dozen people appeared to push through the gate of a bridge between the two countries, slipping through a cordon of Mexican security officials. A larger group waded across the Suchiate River that separates the two countries. Mexican National Guard troops deployed along the banks of the river tried to repel those who waded across and pursued others who reached Mexican soil.

The caravan, which formed last week in Honduras, presented a new test for the Mexican government, which promised the Trump Administration last year that it would step up enforcement, even as President Andrés Manuel López Obrador said he would respect the rights of migrants. Roughly 4,000 Central American migrants waited at the Mexico-Guatemala border on Monday morning, seeking permission to cross through Mexico to the United States, and threatening to enter by force if their request was denied.

Under pressure from President Donald Trump, Mexican efforts to enforce immigration have noticeably increased, with more checkpoints and border controls and the deployment of the national guard. But that hasn't stopped migrants from attempting to transit through the country, including in so-called caravans of hundreds or thousands travelling together for safety.

The group waiting at the border on Monday appeared to be the largest in more than a year, and its size has posed a particular challenge for Mexican security forces.

Migrant caravan reaches Tijuana on US border Show all 30 1 /30 Migrant caravan reaches Tijuana on US border Migrant caravan reaches Tijuana on US border Members of the caravan of Central American migrants climb the border wall in Tijuana, Baja California, Mexico EPA Migrant caravan reaches Tijuana on US border US Border Patrol agents seen through the concertina wire where the border meets the Pacific Ocean AP Migrant caravan reaches Tijuana on US border Central American migrants pray at a temporary shelter in Tijuana AP Migrant caravan reaches Tijuana on US border Darwin, a 12 year old migrant boy from Honduras, looks out from under a tarp while taking refuge at a shelter in Tijuana Reuters Migrant caravan reaches Tijuana on US border Central American migrants line up for a meal at a shelter in Tijuana AP Migrant caravan reaches Tijuana on US border Angel, a 13-year-old migrant from Honduras looks towards the United States past the border fence in Tijuana Reuters Migrant caravan reaches Tijuana on US border Members of the LGBTQ community -who split from a caravan of Central American migrants heading to the US- arrive at the Diversidad Migrante (Migrant Diversity) NGO headquarters, which they will use as shelter, in Tijuana AFP/Getty Migrant caravan reaches Tijuana on US border US military personell install barbed wire fences to stop the passage of Central American migrants EPA Migrant caravan reaches Tijuana on US border Young Honduran migrant Daniel Gamez waits with his family in a line for a meal after arriving with the Central America migrant caravan in Tijuana AP Migrant caravan reaches Tijuana on US border Two women, one carrying a child, walk north after crossing illegally into the United States as a Border Patrol agent moves in to detain them AP Migrant caravan reaches Tijuana on US border epa07165763 People who are part of the first migrant caravan from Honduras start arriving at the border, in Tijuana, Mexico, 14 November 2018. The first migrant caravan advances through the northwest of Mexico as the US has reinforced its military presence at the border. EPA/Joebeth Terriquez Joebeth Terriquez EPA Migrant caravan reaches Tijuana on US border A child looks out the window of a bus upon its arrival at a temporary shelter in Tijuana AFP/Getty Migrant caravan reaches Tijuana on US border Migrants from Honduras dry their clothes in the sand after washing off in the Pacific Ocean AP Migrant caravan reaches Tijuana on US border Central American migrants at a temporary shelter near the US-Mexico border AFP/Getty Migrant caravan reaches Tijuana on US border US police agents stand guard near the US-Mexico border fence AFP/Getty Migrant caravan reaches Tijuana on US border A migrant, who claimed not to be part of the Central American migrant caravan walks on the US-Mexico border fence AFP/Getty Migrant caravan reaches Tijuana on US border Eldin, a migrant man from Honduras, awakes next to his seven year old son Jose while taking refuge at a shelter in Tijuana Reuters Migrant caravan reaches Tijuana on US border Migrants line up for food at a shelter AFP/Getty Migrant caravan reaches Tijuana on US border A man installs concertina wire on top of the border structure on the US side AP Migrant caravan reaches Tijuana on US border Central American migrants sit on an overlook in Tijuana AP Migrant caravan reaches Tijuana on US border A migrant, who is part of a caravan traveling en route to the United States, shouts as he waits to receive food in a shelter in Tijuana REUTERS Migrant caravan reaches Tijuana on US border A man tries to get over a border structure topped with concertina wire AP Migrant caravan reaches Tijuana on US border People who are part of the Central American migrants caravan arrive at a shelter EPA Migrant caravan reaches Tijuana on US border A Central American migrant moving towards the United States in hopes of a better life, is pictured next to the U.S. border fence in Playas de Tijuana, Mexico, on November 13, 2018. - US Defence Secretary Jim Mattis said Tuesday he will visit the US-Mexico border, where thousands of active-duty soldiers have been deployed to help border police prepare for the arrival of a "caravan" of migrants. (Photo by Guillermo Arias / AFP)GUILLERMO ARIAS/AFP/Getty Images GUILLERMO ARIAS AFP/Getty Migrant caravan reaches Tijuana on US border epa07174393 Members of the Central American migrant caravan remain at a shelter in the city of Tijuana in Baja California, Mexico, 18 November 2018. The 5,000 member migrant caravan that entered Mexico on 19 October that stopped this week in the city of Tijuana, bordering the US, are expected to meet in this city on the next day to make a decision about their future, according to local authorities. EPA/JOEBETH TERRIQUEZ JOEBETH TERRIQUEZ EPA Migrant caravan reaches Tijuana on US border Migrants pray at a temporary shelter in Tijuana AP Migrant caravan reaches Tijuana on US border Migrants shower outside a temporary migrant shelter next to the Us-Mexico border fence Getty Images Migrant caravan reaches Tijuana on US border US Border Patrol agents, left, speak with two Central American migrants as they sit atop the border structure AP Migrant caravan reaches Tijuana on US border A Central American migrant looks on through the US-Mexico border fence AFP/Getty Images Migrant caravan reaches Tijuana on US border A migrant stands next to the border fence REUTERS

Mexico's migration agency initially suggested that the migrants could cross the border to register their claims, including the possibility of filing asylum applications. The government initial suggested that many would be given work visas in southern Mexico.

But the migration agency said Sunday that the majority would be deported to their countries of origin. So far, 1,087 of the migrants in the caravan agreed to the registration process. The rest waited at the crossing point, demanding the ability to transit through Mexico without the threat of deportation.

Leaders of the caravan wrote a letter to López Obrador, addressing the president as "Your Excellency", asking that "all the members of the caravan receive the permission to move freely through Mexican territory. We are committed to you and your government to maintain order and discipline in the places where we transit."

The government denied that request. Mexico's migration agency said only that it was "committed to maintaining a safe, orderly and regular migration."

"The legal provisions do not allow for transitory migration," the agency.

By noon Monday, many migrants decided it was time to attempt to cross the border illegally. A few pushed past a group of security personnel on the international bridge that connects Tecun Uman, Guatemala, with Ciudad Hidalgo, Mexico. Many others walked down from the bridge and crossed the river.

Video posted on social media showed men throwing rocks and bottles at uniformed security forces. Troops surround and grapple with men in T-shirts and jeans while other men and women flee.

"We only want to cross to the United States. We don't want to stay" in Mexico, one migrant identified Ingrid said in a video interview with Reuters. "Let me pass. I only want to work. I'm a single mom and I don't want to return to my country where there is nothing."

Mexico has done little to secure the physical border with Guatemala, but it has added checkpoints on the roads that connect the border to the rest of the country. Migrants are detained at those checkpoints and sent to local detention centres, where some wait for months to register with the country's migration agency. Mexico's asylum agency received 66,915 applications for asylum last year, an increase of nearly 126 percent from 2018.

But most migrants who enter Mexico either return voluntarily or are deported to their countries of origin - a marked change from recent years, when it was much easier for Central American migrants to transit through the country with the tacit permission of the Mexican government. Mexico deported more than 117,000 migrants from January through November last year. The United States deported 143,000 immigrants in the 2019 fiscal year.

For members of the caravan trying to make it to the United States, entering Mexico is just one of many challenges. Upon arrival at the U.S. border, Guatemalan asylum seekers are now typically sent back to Mexico to await their cases, a process that can take a year or more. Honduran and Salvadoran asylum seekers may also be sent back to Mexico, under the so-called Migrant Protection Protocols, or they could be sent to Guatemala to seek asylum there.