In response to hundreds of people in the migrant caravan storming the U.S.-Mexico border, near the San Ysidro port of entry, the U.S. military is reaffirming their support to the Department of Homeland Security.

“At the request of U.S. Customs and Border Patrol leaders in the San Diego sector, military engineers moved barricades and military police are part of the additional personnel presence at the San Ysidro Port of Entry today,” U.S. Northern Command said in a statement.

“Department of Defense military personnel will not be conducting law enforcement functions, but are authorized to provide force protection for U.S. Customs and Border Protection personnel and help make sure CBP personnel can perform their assigned Federal functions,” the statement continued. “U.S. Northern Command is providing military support to the Department of Homeland Security and Border protection to secure the southern border of the United States.”

NORTHCOM also released photos of military police practicing non-lethal riot control tactics near the San Ysidro Port of Entry:

Military Police rehearse non-lethal riot control tactics at the San Ysidro Port of Entry, CA and Davis-Monthan AFB, AZ, Nov. 24, 2018. @DeptofDefense military personnel will not be conducting law enforcement functions, but are authorized to provide force protection for @CBP. pic.twitter.com/7i625bWZfn — NORAD & USNORTHCOM (@Norad_Northcom) November 25, 2018

After some of the migrants had illegally crossed the border and threw rocks at border patrol, tear gas was deployed to disperse the crowd:

Here’s moment right before shot bang. You can see some rocks being thrown. pic.twitter.com/p0M9p7Rx4G — WendyFry (@WendyFry_) November 25, 2018

Rodney Scott, chief patrol agent for the San Diego Sector Border Patrol, told CNN on Monday how some in the caravan began to act:

Similarly to what we saw the first wave of the caravan that came up a week ago or so, the group immediately started throwing rocks and debris at our agents, taunting the agents. 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.

Scott added three agents were struck by rocks, but were protected by their riot gear and he said that 42 migrants had illegally crossed the border and were arrested on U.S. soil.