High ranking Customs and Border Protection (CBP) leaders in San Diego say CBP's use of tear gas in border clashes last weekend is under internal review.

The chief agent for San Diego Sector Border Control, Rodney Scott, told USA Today that he asked the agency's internal review board, the Office of Professional Responsibility, to investigate the confrontation.

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"There's a lot of video to go through. There's a lot of reports to look at and read," he said. "It's already been initiated. I've asked for it to be pretty quick."

CBP Deputy Commissioner Robert Perez defended the agents' use of tear gas.

"Our agents were under assault," Perez told USA Today. "They were being rocked, and this was the less lethal way to de-escalate what was a very dangerous situation."

More than a thousand immigrants attempted to force their way through the border Sunday after Mexican federal police tried to contain the situation.

Scott said Monday that the groups were largely composed of men and in some cases moved women and children to the front as the men began to throw rocks at border agents.

Upon being assaulted and seeing immigrants breaking through the border's structural defenses, U.S. authorities released tear gas, dispersing the crowd.

Scott said Monday that American agents arrested 42 people. Mexican authorities say they will deport about 500 people who attempted to force their way into the U.S. "violently" and "illegally."

Still, Mexican authorities reportedly asked the U.S. to conduct an internal review of the use of tear gas.

Sunday's events occurred as thousands of migrants from a so-called caravan from Central America have settled along the U.S.-Mexico border.

Tijuana's government has opened a number of shelters to try and help handle the large numbers that are seeking asylum in the United States.