United States’ (U.S) border agents shot and killed an 23-year-old American man who pulled out a gun and started shooting while trying to drive a truck through a U.S.-Mexican border inspection point at San Diego, police said on Tuesday.

The shooting late Monday sparked panic at the crowded San Ysidro port of entry, where people and vehicles enter the United States from Tijuana, social media video showed.

The San Diego Police Department did not immediately release the man’s identity and it was not clear why he began shooting.

His truck became blocked by another vehicle, and he began shooting at U.S. Customs and Border Protection officers through his truck’s window before getting out and continuing to fire, police said in a statement.

“The officers returned fire, striking the suspect,” the police statement said.

The CBP did not respond to a request for comment. No CBP officers were injured, the police department said.

Eye witnesses described hearing dozens of shots and a panicked scene.

“We hear ‘pop pop,’” Zooch Williams, an eyewitness on the Mexican side of the border, told the NBC 7 news channel.

“We are like, ‘Those were fireworks,’ and my other buddy was like, ‘Those were gunshots.’ ” (Reuters)