DALLAS _ At least four police officers were killed, and at least seven others wounded in an "ambush style" shooting Thursday night by snipers in downtown Dallas near the end of a protest of officer-involved shootings in other cities, Dallas Police Chief David Brown said.
At least one suspect was arrested, and at 12:30 a.m. police were negotiating with another suspect in the parking garage of El Centro College in the 800 block of Main Street.
Brown said officers had "exchanged gunfire" with the suspect, who had declared the "end was near" and said there are "bombs all over the place and downtown."
Brown said it appeared the snipers had some knowledge of the protest's planned route and were "triangulated and elevated" with rifles along the route.
Police do not know how many suspects were involved in the shooting, Brown said.
Three of those killed were Dallas police officers and the fourth was an officer with DART, or Dallas Area Rapid Transit.
Dallas Mayor Mike Rawlings described the shooting "as our worst nightmare" and later said "we as a city, we as a country, must come together and lock arms and heal the wounds that we all feel from time to time."
Rawlings said he had heard from both the White House and Texas Gov. Greg Abbott's office, who had offered assistance.
Dallas police released the photo of one "person of interest" who later turned himself in, but Twitter reaction said the man in the photo was not involved in the shooting.
The protest was nearing the end when rapid gunfire erupted at 8:58 p.m., sending those participating scattering. The protest had been peaceful, but chaos ensued.
Andrea Denmark was walking in the protest and when she was near Main and Griffin streets she saw everyone start running.
"It sounded like firecrackers at first and everyone stopped and we looked around and everyone was OK," said Denmark, 20, of Dallas. "That's when we heard gunshots and everyone started running again. It was so close I could smell it."
A WFAA photographer near the scene recorded the sound of gunfire, which he said was semiautomatic. A reporter said she heard three dozen shots, while some witnesses say they heard 50 to 70 shots and saw the shooter pause to let the protesters go by before targeting officers.
The protest was scheduled in downtown Dallas after Alton Sterling was killed by an officer in Baton Rouge, La., and Philando Castile was killed in Falcon Heights, Minn. The shootings were captured by cellphones.
Some of the officers were taken to Parkland Hospital, where police with rifles were guarding and patrolling the entrance and reporters from four Dallas TV stations were conducting live shots.
A suspicious vehicle was pulled over on Interstate 35E after a person walking down Lamar Street threw a camouflage bag in the car _ a black Mercedes _ and sped off. Police stopped the car on southbound I-35E and were questioning its two occupants.
Police departments from New York to Fort Worth posted comments on Twitter in support of the Dallas and DART officers.
