US agents fired tear gas at hundreds of Central American migrants that climbed over a fence and attempted to rush the border from Tijuana, Mexico into the United States on Sunday.
The San Ysidro border post -- the busiest crossing on the US-Mexico border -- was closed to north and south traffic and pedestrians for several hours following the incident, the US Customs and Border Protection (CBP) office in San Diego, California said.
The migrants, mostly from Honduras, are part of a "caravan" loudly condemned by President Donald Trump.
The shutdown took place only three days after Trump threatened to close the "whole border" with Mexico if "it gets to a level where we're going to lose control or people are going to start getting hurt."
Secretary of the US Department of Homeland Security (DHS) Kirstjen Nielsen accused the migrants of seeking to harm US border patrol personnel "by throwing projectiles at them."
Several hundred made it over the first barrier and were trying to cross a