A live video streaming on Facebook has captured the horror as violence erupted at an anti-violence rally in Dallas, Texas.
Repeated gunshots can be heard echoing through the streets in the video posted by Michael Kevin Bautista, along with sirens screaming.
Two officers crouch beside a fallen colleague, surrounded by police cars, while other armed police storm a building.
Incredibly, Mr Bautista remains calm as he narrates what he can see.
"They're moving in on somebody, I think they might've got somebody," he says.
The scene is chaotic and confusing as police dodge sniper fire, dragging injured officers into police cars.
Later in the video, an officer yells at Mr Bautista to "get off the street".
"They're telling me to go, I gotta go," Mr Bautista says as he leaves. "I got everything man, I got everything."
Five officers were shot dead and another six have been injured when snipers opened fire from elevated positions. Three suspects are in custody but the hunt is continuing for the others responsible.
Police also believe a bomb has been planted and the bomb squad is on the scene.
It took place at an anti-violence Black Lives Matter street protest, one of the many rallies taking place across the US after two black men were shot dead by police in the last 48 hours.