Dallas protest attack: Negotiations underway at parking garage

Dallas police respond after shots were fired during a protest over recent fatal shootings by police in Louisiana and Minnesota, Thursday, July 7, 2016, in Dallas. Snipers opened fire on police officers during protests; several officers were killed, police said. AP

DALLAS — Dallas Police Chief David Brown says three people are in custody after snipers opened fire on police officers during protests and says a fourth person is exchanging gunfire with officers.

READ: Dallas police chief: 4 officers killed, 7 injured at protest

Brown said at an early Friday morning news conference that authorities are negotiating with a suspect in a downtown parking garage who has been exchanging gunfire with officials.

The chief says the suspect is not cooperating and has told negotiators he intends to hurt more law enforcement officials.

The shooting attack killed four officers and injured seven others. It came amid protests over two recent fatal police shootings of black men.

Brown says authorities are not certain all suspects have been located.