DALLAS — A military veteran carried out the worst attack on police in Dallas’ history on Thursday evening, killing five officers and wounding seven more before he was killed by a robot-controlled bomb.

The attack took place near the end of a protest that started at 7 p.m. in Belo Garden in downtown Dallas, and marched towards Main Street Garden and back to Commerce Street.

At 8:58 p.m. shots were fired at the officers. A witness said the gunman, identified later as Micah Xavier Johnson, was shooting at officers behind a pillar, the New York Times reported.

Johnson was then seen running past El Centro College down Elm Street, but somehow ended up on the second floor of a garage near the college.

According to the New York Times, police cornered Johnson in the garage and started negotiating with him around 11:45 p.m. The negotiation broke down after several hours and the two sides exchanged gunfire.

“He said he was upset about the recent police shootings,” the New York Times quoted Dallas Police Chief David O. Brown as saying. “The suspect said he was upset at white people. The suspect stated he wanted to kill white people, especially white officers.”

Police then attached a bomb onto a bomb-disposal robot and sent it to Johnson. He was killed after police detonated the robot bomb.

Investigators discovered bomb-making materials, rifles and a journal of combat tactics in Johnson’s home during a search on Friday.