Updated | Fifth US police officers dies after sniper shooting

Gunfire broke out as demonstrators marched through the city killing five police officers.

One suspect has been taken into custody after a shootout with police, while a person of interest turned himself in, Dallas police tweeted.

The protests were sparked by the deaths of Philando Castile in Minnesota and Alton Sterling in Louisiana, two black men who were shot dead at the hands of white police officers.

The gunfire broke out at around 20:45 local time on Thursday (02:45 CET Friday).

Dallas Police Chief David Brown said 11 officers were shot "ambush style" by the sniper fire, killing three officers on the scene.

The police later tweeted that a fourth  and now a fifth officer has died. Some six other officers are still in hospital, and the severity of their condition is not known.One of those killed was a transport police officer.

The police said it appeared that two snipers had fired from "elevated positions" during the protest rally.

"We believe that these suspects were positioning themselves in a way to triangulate on these officers from two different perches... and planned to injure and kill as many law enforcement officers as they could," he said.

Philando Castile was shot dead at a traffic stop in St Paul, Minnesota , on Wednesday, while Alton Sterling was killed by police a day earlier in Baton Rouge, Louisiana.

US President Barack Obama said "all fair-minded people should be concerned" about the frequent police killings of black Americans.

Pointing to statistics showing African-American citizens are far more likely to be shot by police by whites, Obama called on law enforcement to root out internal bias, the BBC reports.

"When incidents like this occur, there's a big chunk of our fellow citizenry that feels as if it's because of the colour of their skin, they are not being treated the same,'' he said. "And that hurts."