A “violent mob” of migrants threw rocks at U.S. Customs and Border agents on New Year’s Eve after attempting to cross the border in San Diego, according to the Department of Homeland Security.

Border agents were forced to use smoke, pepper spray and CS gas to suppress the migrants after they threw rocks over the border fence, a DHS press release states.

Young migrants also attempted to cross over concertina wire on the border fence, leaving agents unable to assist them because of “the large number of rocks being thrown at them.”

“Several teenagers, wrapped in heavy jackets, blankets and rubber mats were put over the concertina wire,” stated DHS. “Border Patrol agents witnessed members of the group attempt to lift toddler sized children up and over the concertina wire and having difficulty accomplishing the task in a safe manner. Agents were not in a position to safely assist the children due to the large number of rocks being thrown at them.”

Twenty-five migrants–including two teenagers–were apprehended by border agents during the altercation.