A gun attack on police in the US city of Dallas has left four officers dead and seven injured. Here's what we know so far about the attack:
Suspects have already been detained following the shootings.
Dallas police said three suspects were taken into custody following the shootings, while a fourth person was still involved in gunfire with SWAT officers by 1am on Friday, local time.
The initial search for a gunman stretched throughout central Dallas - an area of hotels, restaurants, businesses and some residential apartments - in a chaotic scene involving helicopters and armed officers on the street corners.
Police also said a suspicious package was being secured by a bomb squad following the attack.
The attack happened during a protest against police violence.
The gunfire broke out around 8.45pm local time on Thursday while hundreds of people were gathered to protest against fatal police shootings this week in Baton Rouge, Louisiana, and suburban St Paul, Minnesota.
Dallas police chief David Brown told reporters the snipers fired "ambush style" upon the officers.
Footage from the scene showed protesters marching along a street about half a mile from City Hall before shots erupted, scattering the crowd as they sought cover.
"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 in the area, told the newspaper that the shooters "were strategic. It was tap, tap, pause. Tap, tap, pause".
The protest itself came in response to a number of recent police shootings.
The gunshots in Dallas came amid protests nationwide over the recent police shootings of black people.
Philando Castile was fatally shot by a Minnesota police officer while he was in a car with a woman and a child in St Paul.
A day before the Castile shooting, Alton Sterling was shot in Louisiana after being pinned to the pavement by two white officers. Moments from both incidents were captured on video.