Bloodiest day for US police since 9/11 sees 'lone' shooter murders five
Gunman angered at law enforcement killings of two black men is taken out by a robot bomb after negotiations to end stand-off in Dallas city centre car park
A suspect in the gun attack on police in the heart of Dallas told officers he was upset over recent shootings by officers of black men and wanted to kill white people, according to officials.
The suspect, named as Micah Johnson (25), died after a stand-off with police following the attacks which left five officers dead and seven injured.
The killings happened during protests over two recent fatal police shootings of black men.
Police Chief David Brown said Johnson told negotiators he was acting alone and was unaffiliated to any group.
Mr Brown told a Press conference that officers killed Johnson with a robot-delivered bomb after hours of negotiations in a city centre parking garage failed, and during which he made threats about bombs.
Police sealed off the city centre but later tweeted that primary and secondary sweeps for explosives were complete and none were found.
Although Johnson apparently said he had acted alone, it remains unclear if that was the case. Mr Brown said earlier that three other suspects were in custody, but he declined to discuss those detentions.
The gunfire broke out as hundreds of people gathered to protest over incidents in Baton Rouge, Louisiana, and St Paul, Minnesota.
The Dallas shootings claimed the lives of four city police officers and one member of Dallas Area Rapid Transit, which operates buses and the largest municipal rail system in the state.
Mr Brown told reporters snipers fired "ambush style" on the officers. Two members of the public were wounded. Video footage from the scene showed protesters marching about half-a-mile from City Hall when the shots erupted and the crowd scattered, seeking cover.
Mr Brown said it appeared the shooters "planned to injure and kill as many officers as they could". The attacks made Thursday the deadliest day for US law enforcement officers since the September 11 terrorist attacks in 2001. The search for the shooters stretched throughout the city centre.
The scene was chaotic, with helicopters hovering overhead and officers with automatic rifles on street corners.
One witness, Devante Odom (21), told the Dallas Morning News: "Everyone just started running. We lost touch with two of our friends just trying to get out of there."
Carlos Harris, who lives nearby, told the newspaper the shooters "were strategic. It was tap, tap, pause. Tap, tap, pause".
Footage posted on social media appeared to show a gunman at ground level exchanging fire with a police officer who was then felled. Authorities have not determined whether any protesters were involved with or were complicit in the attack.
One woman was taken into custody in the same parking garage as the stand-off, Mr Brown said. Two others were taken into custody during a traffic stop.
People were asked to stay away from the city centre as it was an active crime scene. Meanwhile, Dallas Area Rapid Transit said in a statement that its officer, Brent Thompson (43), who was married just two weeks ago, was the first officer killed in the line of duty since the agency formed its own police department in 1989.
Theresa Williams said one of the injured civilians was her sister, 37-year-old Shetamia Taylor.
Ms Taylor was at the protests with her four sons, aged 12 to 17, and threw herself across them when the shooting began. She was undergoing surgery after being shot in the right calf.
Texas governor Greg Abbott released a statement saying: "In times like this we must remember, and emphasise, the importance of uniting as Americans."