Earlier in the morning, a group of Central Americans staged a peaceful march to appeal for the U.S.to speed up the asylum claims process, but their demonstration devolved as they neared the crossing with the USA and some saw an opportunity to breach the border.
As of now, more than 8,200 migrants from various Central American countries have reached Mexico, with around 7,400 of them staying near the cities of Tijuana and Mexicali, located right on the border with the United States, the ministry specified. Migrants sought to squeeze through gaps in wire, climb over fences and peel back metal sheeting to enter.
"Children screamed and coughed. Once our agents were assaulted and the numbers started growing, we had two or three agents at a time initially, facing hundreds of people at a time, they deployed tear gas to protect themselves and to protect the border".
As the chaos unfolded, shoppers just yards away on the USA side streamed in and out of an outlet mall, which eventually closed.
U.S. Homeland Security Secretary Kirstjen Nielsen said Customs and Border Patrol personnel "were struck by projectiles thrown by caravan members", and the agency said that prompted officers to use the tear gas "because of the risk to agents' safety".
Traffic also was jammed for parts of the southbound stretch of Interstate 15 into Southern California from Las Vegas, including in the Cajon Pass.
But the meeting of the incoming administration officials in Mexico City to discuss a response was derailed by the chaotic events along the Ysidro border crossing.
USA officials have said for months that they were working with Mexico to find solutions for what they have called a border crisis.
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The new drama began with remarks Trump made on Tuesday in which he went after a judge who ruled against his migrant asylum order. It's not unusual for those challenging a president's policies to sue in courts they consider likely to back their claims.
"With the help of the [Mexican] National Institute of Migration, people whose participation in these acts of violence [on the USA border] has been fully proven will be immediately deported", the ministry added. Close to 3,000 migrants took Mexico up on the offer.
The policy, known as "Remain in Mexico", was formulated by the Trump administration to deal with the thousands of immigrants seeking asylum in the U.S.in the caravan.
Numerous migrants are seeking to apply for asylum in the USA, but as James Fredrick reported for NPR, fewer than 100 asylum petitions per day are being processed at the San Ysidro entry point.
"Mexico should move the flag waving Migrants, many of whom are stone cold criminals, back to their countries", Trump tweeted.
This video shows migrants fleeing from the border next to the Tijuana River.
"Would be very SMART if Mexico would stop the Caravans long before they get to our Southern Border, or if originating countries would not let them form (it is a way they get certain people out of their country and dump in US No longer)", he wrote.
Mexico's Interior Ministry said Sunday the country has sent 11,000 Central Americans back to their countries of origin since October 19.