Trump asks Mexico to send migrants back to countries of origin after border patrol fires tear gas

President Donald Trump tweeted Monday that Mexican officials should ship the thousands of Central American migrants seeking entry into the U.S. back to their countries of origin by any means necessary, claiming that "many" are "stone cold criminals."

Trump suggested that Mexico send the migrants back to countries such as Guatemala and Honduras by airplane, bus, or "anyway you want." The president also threatened to shut down the U.S. Southern Border "permanently" if needed.

The tweet comes after U.S. Customs and Border Protection officials fired tear gas on hundreds of migrants who sought to enter the U.S. on Sunday near San Diego. That interaction led to U.S. officials shutting down the San Ysidro Port of Entry between San Diego and Tijuana for more than six hours.

In a statement, border patrol said it used tear gas and pepper spray after several migrants tossed rocks at agents, who were struck. No injuries were reported.

"DHS will not tolerate this type of lawlessness and will not hesitate to shut down ports of entry for security and public safety reasons," Department of Homeland Security Secretary Kirstjen Nielsen said in a Sunday statement.

Some migrants, meanwhile, said they sought to cross over illegally after they were denied access at the port of entry, where they could claim asylum. It is not illegal to seek asylum.

The hundreds of migrants who assembled along the Mexican side of the border on Sunday morning were a part of a larger group of about 6,000 who crammed into shelters in Tijuana. Many of the migrants are fleeing violence in their home countries.

Images of tear gas being fired at the migrants, some of whom were young children, led to an outcry on social media.

The Sunday episode came one day after the Trump administration and Mexico's incoming government appeared to be at odds over a deal that would keep asylum-seekers in Mexico while awaiting their asylum cases to be processed in the U.S.

The current system allows for asylum-seekers to remain in the U.S. while those cases are processed.