Thousands of people travelling across Central America en masse to the US are stuck on Mexico’s southern border after a failed attempt to enter the country.
Some of them broke through Guatemalan border fences but then clashed with Mexican riot police in no man’s land.
On Friday, US President Donald Trump thanked Mexico for its efforts in stopping the caravan of migrants.
The migrants, mostly from Honduras, say they are fleeing violence and poverty, and include women and children.
President Trump, who has threatened to close down the US border and cut aid to countries allowing the caravan to pass, said the military would be called upon if needed.
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“They might as well turn back, they’re not coming into this country,” he told reporters on Friday.
After talks on border security in Mexico, Secretary of State Mike Pompeo said the situation was reaching “a moment of crisis”.
What happened on the border?
Many of the migrants temporarily broke through barriers on a bridge which crosses the river border between Guatemala and Mexico.
Dozens of Mexican police in riot gear fired tear gas to force them to retreat into no-man’s land after being attacked with stones.
A number of migrants jumped into the Suchiate river to reach rafts, while others either turned back towards Guatemala or simply sat down on the bridge.
Several people were reportedly injured in the clash, including migrants, police and journalists.
One woman nursing a baby told AFP she had lost two of her children in the chaos.
“We’re running away from violence, and we arrive here and they just hit us more,” Marta Ornelas Cazares, 28, said.
“I don’t know what happened, I thought we were going to cross peacefully and then suddenly there were rocks flying and tear gas.”
The Mexican authorities said those with valid passports and visas would be allowed in immediately, though this is believed to apply to only a minority of the migrants.
They warned that anyone without papers would have to apply for refugee status or turn back, and anyone who crossed illegally would be detained and deported.
According to AFP, they started to allow a small number of people – including women and children – who were seeking refugee status to pass the border late on Friday. They were put on to trucks and taken into shelters.
An estimated 3,000 people are said to have joined the journey of nearly 2,800 miles (4,500km) – mostly on foot – which began in San Pedro Sula, Honduras, more than a week ago.