More than a dozen migrants have been arrested at the U.S.-Mexico border for trying to cross illegally, a San Diego Border Patrol source told Fox News.

One group was arrested on the beach in an area called Playas de Tijuana. Another, larger group, was apprehended in the mountains east of the San Diego border community, Otay Mesa.

Separately, a fight broke out Wednesday night in Tijuana between Mexicans and the caravan members: “The migrants complained that the locals were yelling: ‘Go home. We don’t want you here!’ Members of the caravan complained to reporters that local police made no attempt to break up the fight.”

About two dozen migrants camped out along the border fence, while other went to shelters or are sleeping in tents.

Roughly 400 migrants arrived in Tijuana by bus on Tuesday evening, and are the first of the caravan to reach the border. Thousands more migrants are expected to arrive in the next few days.

Of those already at the border, the New York Times reports that a few of them were already looking to make appointments with U.S. border officials to present their cases for sanctuary. However, most “appear to be biding their time and considering their options, including seeking sanctuary in the United States, trying to cross illegally or remaining in Mexico.”

Defense Secretary James Mattis visited the border yesterday and defended the deployment of thousands of troops to the U.S.-Mexico border, calling it “a moral and ethical mission to support our border patrolmen.”

Mattis said, “border security is part of national security” and emphasized the mission of the military was to support U.S. Customs and Border Protection as the migrant caravans arrive in the coming weeks.

Currently, about 7,000 soldiers and Marines have arrived in Texas, Arizona, and California, with President Trump warning that another 8,000 could be deployed if needed.