Three people were arrested and a fourth suspect was exchanging gunfire with authorities in a parking garage downtown, Dallas Police Chief David Brown informed early Friday morning.
The suspect was not cooperating and told negotiators he plans to hurt more law enforcement officials, the chief said.
The gunfire started around 8.45 p.m. local time, on Thursday when hundreds of people had gathered to protest fatal police shootings this week in Baton Rouge, Louisiana, and suburban St. Paul, Minnesota. The snipers reportedly fired "ambush style" upon the officers.
It appeared the shooters "planned to injure and kill as many officers as they could," Brown said.
"Everyone just started running," an eyewitness, Devante Odom, 21, told The Dallas Morning News. "We lost touch with two of our friends just trying to get out of there."