A protest against police brutality in the US state of Texas turned deadly as eleven police officers were shot on Thursday evening.

Dallas police Chief David Brown says that two snipers carried out the attack while waiting in elevated positions. Three officers are dead, while two are currently undergoing surgery. Three others are still in critical condition.

“Let’s all come together and support our police officers,” he said. “I’ve never been as proud. I believe we’ve got to one of the best forces in the nation, and we’ve done things with civil rights in the right way, and we’ve done it for the safety of our citizens. So please, let’s come together now as a city.”

No suspects have been caught, though Brown told reporters that one is “cornered.”

Authorities believe that the suspects also threatened to set off a bomb in downtown Dallas.

Protests have been spreading around the United States after police were filmed killing two African-American men.