Chicago officials have publicly released body-camera video footage showing a policeman fatally shoot a 13-year-old boy in an alley more than two weeks ago. Thursday's release of the graphic video sparked peaceful protests in Chicago, with demonstrators calling for justice in the death of Adam Toledo as tensions remain high between US police and many of the communities they serve. High-profile police killings of people of colour have flamed unrest across the country, with observers watching closely in the trial of a former Minneapolis cop charged with murdering George Floyd last year. The nine-minute video begins by showing an unidentified police officer getting out of his squad car and running after Toledo, who was Latino, in an alley at 2.30am on March 29 in Little Village, a neighbourhood on the city’s West Side. In the officer's body-camera video he can be heard yelling at Toledo to stop before he catches up to him and orders him to show him his hands. Toledo appears to raise his hands right before the officer fires one shot and then immediately runs to the boy as he falls to the ground. "Shots fired, shots fired. Get an ambulance over here now," the policeman is heard saying in the video. "Stay with me, stay with me," the officer says. "Somebody bring the medical kit now!" The Chicago Police Department said immediately after the incident that Toledo had a gun in his hand. In the video it does not seem that Toledo had a gun in his hand when he was shot. But video from a security camera behind the victim taken a split-second before the shooting appears to show Toledo tossing something behind the fence behind him. About five minutes and 30 seconds into the video, an officer shines a flashlight on a handgun lying a metre or two from where officers work frantically to save Toledo's life, giving him CPR. Officers were chasing Toledo and a man after they received notification of shots fired in the area, the department said. "There were a number of forces that met up at 2.30 in the morning on March 29 in an alley, and, simply put, we failed Adam," Chicago Mayor Lori Lightfoot said during a news conference before the video was released. The city's Civilian Office of Police Accountability also released about 33 data files, including other police body camera videos, footage from nearby security cameras and documents related to the incident. The incident, with Sunday's fatal police shooting of Daunte Wright in a Minneapolis suburb and the murder trial of former Minneapolis police officer Derek Chauvin in the May 2020 death of George Floyd, has raised tensions in Chicago. "Chicago, as well as way too many parts of our country, has a long legacy of police violence and police misconduct that have left far too many residents, especially those who are black and brown, in a constant state of fear and pain," Ms Lightfoot said. City officials urged people to remain calm as they prepared for civil unrest after the release of the video footage. They said more police officers and city equipment would be in place to protect businesses during any unrest. Like some other American cities, Chicago experienced riots and looting after Floyd's death, which was also caught on video. Toledo's family in a statement released to local media said that they appreciated the support they had received from the community and were grateful that protests in Chicago over the past few days were peaceful. “We pray that for the sake of our city, people remain peaceful to honour Adam’s memory and work constructively to promote reform," the family said.