DALLAS — Police Chief David Brown says a suspect in the overnight attack that killed five police officers, wounded seven others and wounded two civilians said he was upset over the recent police shootings of black men and wanted to kill white people.

Brown said at a news conference Friday that the suspect made the comments before he was killed by an explosive used by police.

The shooter also said he acted alone, Brown said.

He says his department and their families are grieving and that the divisiveness between police and the public must stop.

Authorities say snipers opened fire on police officers during a peaceful protest in downtown Dallas Thursday night over the recent fatal shootings of black men in Louisiana and Minnesota.

Authorities say three other suspects were arrested in the incident. Brown declined to discuss the three detentions and said police still didn't know if investigators had accounted for all participants in the attack.

A man wrongly identified by Dallas police as a suspect in a sniper attack on police says he turned himself in and was quickly released.

The Dallas Police Department put out a photo on its Twitter account late Thursday of a man wearing a camouflage shirt and holding a rifle with the message: "This is one of our suspects. Please help us find him!" The tweet remained on the account early Friday morning.

The man in the photo, Mark Hughes, tells Dallas TV station KTVT that he "flagged down a police officer" immediately after finding out he was a suspect. He says police lied during a 30-minute interrogation, telling him they had video of him shooting.

Videos posted online show Hughes walking around peacefully during the shooting and later turning over his gun to a police officer.

Dallas Area Rapid Transit officials say three DART police officers wounded by snipers during the protest are expected to recover.

A DART statement Friday identified the agency's three wounded personnel as 44-year-old Officer Omar Cannon, 32-year-old Officer Misty McBride and 39-year-old Officer Jesus Retana. DART spokesman Morgan Lyons did not release details of the injuries, but said all three should recover.

Officer Brent Thompson was the first DART officer killed in the line of duty since the transit agency formed a police department in 1989. Thompson was 43 and had worked as a DART officer since 2009.

Thompson was a newlywed whose bride also works for the police force.

Dallas Area Rapid Transit police Chief James Spiller described Officer Brent Thompson on Friday as a "courageous" and "great guy."

Mayor Mike Rawlings says a total of 12 police officers and two civilians were shot during the protest march. Rawlings said Friday that he does not believe that any of the wounded victims have life-threatening injuries.

Copyright 2016 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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