At least five police officers have been shot dead in the United States at protests over recent police killings of black men. The deaths have been confirmed by the Dallas Police Department.
An "intensive search" for suspects was under way.
Gunfire broke out late on Thursday during an otherwise peaceful protest over two recent fatal police shootings in Minnesota and Louisiana. The sound of shots sent marchers running and police taking cover.
Dallas police chief, David O Brown, said two gunmen shot at police officers from "elevated positions", hitting at least 11 of them. At least three of the wounded were in a critical condition, he said.
Police released a photo of someone they called a "person" of interest and later said he had handed himself in. A second suspect was also in custody, they said.
Firefighters and police at the scene were keeping people away; dozens of police cars with their lights flashing were there.
"Everyone just started running," Devante Odom, 21, told The Dallas Morning News. "We lost touch with two of our friends just trying to get out of there."
Carlos Harris, who lives downtown told the newspaper that the gunmen "were strategic. It was tap tap pause. Tap tap pause."