An unknown assailant in Mexico assaulted a U.S. Border Patrol agent with a large rock as the agent patrolled the border in Calexico, California. The assault occurred as the agent prepared to take a migrant into custody who had just illegally crossed the damaged border barrier.

Shortly before noon on Saturday morning, an El Centro Sector Border Patrol agents observed a migrant illegally cross the border barrier near 1st Street and Dool Avenue in Calexico. The migrant entered the U.S. through “an old dilapidated section of wall,” according to information provided by El Centro Sector Border Patrol officials.

@CBPElCentro had one of its #BorderPatrol agents assaulted while patrolling in #Calexico. Our Agents face dangers like this one while maintaining the security of our nation. pic.twitter.com/MLleKATPIo — CBP El Centro (@CBPElCentro) June 24, 2019

As the agent responded in his patrol vehicle, an unidentified individual in Mexico threw a softball sized concrete rock through the breach in the wall. The rock reportedly entered the Border Patrol agents vehicle through the driver side window striking the agent in the face, officials stated.

The assailant fled the scene to avoid apprehension by Mexican law enforcement officials.

“The rock thrown at the agent caused a serious laceration above the eye which required medical attention,” El Centro officials reported. Agents arranged transportation for the injured Border Patrol agent to a local hospital for treatment and evaluation.

“Our Border Patrol agents work in extremely dangerous situations and under heavy duress,” El Centro Sector Chief Patrol Agent Gloria I. Chavez said in a written statement. “However, our agents continue to perform at an exceptionally high level carrying out their duties with integrity and compassion.”

Agents placed the migrant who illegally entered the U.S. into custody and held him for questioning. The assault will be investigated by the FBI.