A U.S. Border Patrol agent was struck with a grapefruit-sized rock while patrolling the California and Mexico border Saturday night and was hospitalized.

Supervisory Border Patrol Agent Michael Scappechio tells KTLA-TV that the agent was traveling around 20 m.p.h. on an ATV in the Otay Mesa, California, and Tijuana, Mexico border area this weekend when he was hit in the chest with the large rock. After crashing the ATV, the injured Border Patrol agent moved the vehicle off the road and called for emergency backup.

First responders to the scene say they spotted a cadre of people on the Mexico, south side of the border fence, KTLA reports. Scappechio says the agent was hospitalized for his injuries sustained from both the rock impacting his chest and his all-terrain vehicle crash.

The responding U.S. Border Patrol agents who came to the Otay Mesa border area used tear gas to disperse the group they say was attempting to cross the border illegally into the United States. Mexican authorities were notified and helped U.S. law enforcement in finding the potential and alleged illegal immigrants on the Mexico side of the border.

In November, U.S. Border Patrol agent Rogelio Martinez, 36, was struck and killed along the southern border of Texas after authorities said he was “attacked” by potential illegal immigrants.