
Mexico faces a mounting crisis at its southern border, where thousands of migrants remain crowded and pressing for entry after some groups managed to break through.

Secretary of State Mike Pompeo rushed to Mexico City on Friday to confer with his counterpart, and declared the situation is reaching 'a moment of crisis' and posing 'a challenge for American sovereignty.'

Mexican Foreign Minister Luis Videgaray Caso insisted Mexico would not cave to pressure to detain the migrants, saying: 'Mexico's migration policy is for Mexico to decide.'

As night fell at the border with Guatemala, many migrants prepared to camp out on the bridge over the Suchiate River, which had earlier been the scene of chaos and violent clashes with riot police.

Aerial view of a Honduran migrant caravan heading to the US, as it is stopped at a border barrier on the Guatemala-Mexico international bridge in Ciudad Hidalgo, Chiapas state, Mexico on Friday

Following clashes with Mexican police, thousands of bedraggled migrants sat down on the bridge and prepared to camp

The gated entry into Mexico via the bridge has been closed. Migrants pressed against the gates and pleaded for entry

'We're staying here until they open this fence,' said Adonai Sanchez, 36, who was traveling with his three nephews, aged two, three and 14, as they set up camp on the bridge.

In the twilight dusk, the migrants' frustration turned to despair as women clutching small children took up the rows in front of the gate pleading with the Mexican federal police.

Some migrants yelled 'We are hungry!' Others wailed that they had children while others set up tarps to prepare for the night sleeping on the increasingly dirty and befouled bridge.

'Please, it is night. Let us pass,' Alba Luz Giron Ramirez, a former shop employee and mother of three, pleaded to the officers.

Giron said they had come from San Pedro Sula, Honduras, and that gangs had killed her brother and threatened her.

'We want them to give us permission to go to Mexico,' her 5-year-old son Ramon said in a child's voice. 'We wouldn't stay.'

Honduran migrants taking part in a caravan heading to the US, rest as they arrive at the border crossing point with Mexico

As night fell at the border with Guatemala, many migrants prepared to camp out on the bridge over the Suchiate River

Honduran migrants taking part in a caravan heading to the US, rest as they arrive at the border crossing point with Mexico

Groups of Honduran migrants rest while waiting to be able to enter Mexico on the bridge from in Tecun Uman, Guatemala

Honduran migrants, part of a caravan trying to reach the U.S., are seen on the bridge that connects Mexico and Guatemala

A Honduran migrant looks at his phone on the bridge that connects Mexico and Guatemala in Ciudad Hidalgo, Mexico

Alison Danisa wept as she knelt in the garbage already piling up on the bridge, clutching her naked 11-month-old infant to her breast.

'We have suffered so much. She has a fever and we brought nothing,' she said, showing the baby's bare bottom to indicate they had no diapers.

A Mexican marine official with a loudspeaker approached the gate and told migrants they would be taken in trucks to 'a humanitarian attention center' in Tapachula, a border city in the Mexican state of Chiapas. But the official did not say when this would happen.

The scene remained tense at the final border barrier, a tall fence of white metal bars that had been the scene of violent clashes just hours earlier.

Chanting 'Yes we can!' and 'Mexico! Mexico!' migrants earlier climbed or violently tore down a series of barriers, flooding across the bridge.

The migrants could be seen passing babies overhead through the crowd. Women holding crying children by the hand or pressing their infants to their chests streamed past the broken metal barriers and onto the bridge.

Earlier on Friday, groups of migrants stormed the border gate on the Mexican side of the bridge, carrying Honduran flags

Honduran migrants await access to Mexico on the bridge that crosses the Suchiate River from Guatemala

The crowd lifted up barriers with ease, discarding them in the street as they carried on before being met with a line of police

A baby is squashed between its mother and Mexican police as the migrants try to force their way into the country on Friday

A father shields his baby daughter from the chaos as he retreats from police. Sources on the border tell DailyMail.com the police threw tear gas into the crowds before suddenly deciding to let some women and children through

The crowd broke down barriers and rushed towards the riot police, hellbent on getting through them no matter the cost

A Honduran migrant with a minor in their arms shouts at members of the Mexican police at the border crossing on Friday

The migrants hurled rocks and other objects at hundreds of riot police, who responded with rubber bullets and tear gas. At least six Mexican federal police officers were injured in the clashes.

About 50 managed to push their way through before officers unleashed pepper spray and the rest retreated, joining the sea of humanity on the bridge.

Acner Adolfo Rodriguez, 30, one of the last migrants through the breached Guatemala border fence, said he hoped to find work and a better life far from the widespread poverty and gang violence in Honduras, one of the world's deadliest countries.

'May Trump's heart be touched so he lets us through,' Rodriguez said.

Back on the bridge, scores of bedraggled migrants carrying backpacks and small children simply sat down on the bridge. Some said that they had been teargassed.

'We're running away from violence, and we arrive here and they just hit us more,' sobbed 28-year-old Marta Ornelas Cazares, who was nursing her baby -- but had lost her other two children, aged 10 and 15, in the turmoil.

'I don't know what happened, I thought we were going to cross peacefully and then suddenly there were rocks flying and tear gas,' she said.

Some migrants used a rope to jump off the bridge and swim across the river or hitch a ride on the many rafts that cross it regularly, charging a dollar or two for the crossing.

Migrants tired of waiting to cross into Mexico jumped from a border bridge into the Suchiate River on Friday

A Honduran migrant, part of a caravan trying to reach the U.S., jumps from the bridge that connects Mexico and Guatemala

Migrants used a rope bridge to ford the river and cross into Mexico, avoided border guards on the bridge above

Others used makeshift rafts made out of discarded car tires to cross the Suchiate River from Guatemala into Mexico

Honduran migrants, part of a caravan trying to reach the U.S., are seen after crossing the Suchiate River into Mexico

Manelich Castilla, the head of Mexico's federal police, said at the bridge that his officers had restored order after the rush of migrants towards the border, and would begin allowing people to be processed in an orderly fashion.

Mexican authorities insisted the migrants would have to file asylum claims one at a time in order to enter the country.

They began letting them through in a trickle - first women and children, who were ushered onto trucks and taken to shelters.

Jose Brian Guerrero, a 24-year-old Honduran traveling with neighbors and his extended family, said he had joined the caravan to escape violent street gangs, and to find work.

'There's nothing for us in our country,' said Guerrero, who used to sell beans in Honduras.

Several migrants at the Guatemala-Mexico border spoke of entire neighborhoods leaving their homes to join the trek after calls circulated on social media to form a caravan to head toward the U.S.

At least one splinter group from the main caravan managed to cross the river and is being tracked by the U.S. government as it heads north, according to documents reviewed by NBC News.

Another large caravan of roughly 1,000 Hondurans recently crossed into El Salvador heading north, threatening to exacerbate the border crisis.

Honduran President Juan Orlando Hernandez (above) said he had spoken to his Guatemalan counterpart Jimmy Morales for clearance to send civil protection personnel to help the Hondurans and to find transport for those wanting to return

In Honduras, a girl who hopes to migrate to the US kneels in front of a police checkpoint at the Agua Caliente border crossing on Friday. Honduran authorities have intensified immigration control measures at the checkpoint bordering Guatemala

In Tegucigalpa, Honduras protesters burn tires at the US embassy during a march in support of the caravan of migrants on Friday. Hundreds of people marched to express their solidarity with the caravan of migrants trying to reach the United States

Honduran former deputy Bartolo Fuentes, who was deported from Guatemala for organizing the massive migrant caravan heading to the US, speaks during a demonstration in front of the US embassy in Tegucigalpa, Honduras on Friday

On Friday evening, Honduran President Juan Orlando Hernandez said he had spoken to his Guatemalan counterpart Jimmy Morales for clearance to send civil protection personnel to help the Hondurans and to find transport for those wanting to return.

'I also asked authorization to hire ground transportation for anyone who wants to return and an air bridge for special cases of women, children, the elderly and the sick,' Hernandez tweeted. 'We'll continue this operation for as long as is necessary.'

Shortly afterwards, Guatemala's government tweeted that Hernandez would meet Morales on Saturday in Guatemala City to implement a strategy for returning the Honduran migrants.

Late Friday night, Mexican President Enrique Pena Nieto said in an address to the nation that a large group of migrants had 'tried to enter Mexican territory irregularly, attacking and even hurting some elements of the Federal Police.'

'Mexico does not permit and will not permit entry into its territory in an irregular fashion, much less in a violent fashion,' he said.

Speaking in Arizona on Friday, President Donald Trump said he 'appreciated very much' Mexico's efforts to stop the caravan.

'If that doesn't work out, we're calling up the military - not the (National) Guard - we're calling up the military,' he told reporters. 'They're not coming into this country.'

You got some bad people in those groups. You got some tough people in those groups, and I'll tell you what, this country doesn't want them!' Trump said of the migrant caravan at a rally on Friday

U.S. Secretary of State Mike Pompeo and Foreign Affairs Secretary of Mexico Luis Videgaray (right) deliver a press conference as part of U.S. Secretary of State official visit to Mexico at Secretariat of Foreign Affairs on Friday

'These are some bad people. These aren't little angels. These are some hardened criminals coming up. And we're not letting them in,' he told reporters on Friday during a defense round-table in Arizona.

'They put all the women and children up front, to show you how brave they are,' he said.

When a reporter challenged him to produce evidence that there were criminals among the migrants, Trump scoffed: 'Oh please, please, don't be a baby.'

'Take a look, these are hardened criminals, tough people,' he said.

Trump also reiterated his claim, so far without evidence, that Democrat operatives had organized the caravan to stir chaos ahead of the mid-term elections.

In contrast to the earlier caravan six months ago, which had advanced into Mexico before officials began intensive efforts to process the migrants, the Mexican government turned its attention to the new group right on its southern border.

Honduran migrants taking part in a caravan heading to the US rest as they arrive at the border crossing point with Mexico

Mexico's government has sought assistance from the United Nations High Commissioner for Refugees.

On Friday morning, Videgaray said the caravan had close to 4,000 people and that the migrants could individually present their claims to enter Mexico or seek refugee status.

'We haven't had a caravan or group of this size seeking refuge at the same time, that's why we've sought the support of the United Nations,' he told Mexican television.

Mexico says the migrants without a legitimate case to claim refuge in Mexico will be returned to their countries of origin. A Mexican official, speaking on condition of anonymity, said the country had the capacity to process around 200 people a day.

On his trip to Mexico City on Friday, Pompeo said that he had stressed the importance of stopping the caravan before it reaches the U.S. border in his conversation with Foreign Minster Videgaray Caso.

Ultimately, he said, Mexico will have to decide how it wants to deal with the crisis.

'The way that Mexico will handle this, the way that you will handle this, is your sovereign decision,' Pompeo said, turning to address Videgaray Caso. 'Mexico will make its decision.'