The FBI and authorities in Minnesota have launched investigations into the death of an African American man after an incident, captured on video, in which a white Minneapolis police officer knelt on his neck as he lay on the ground. In the footage the man, later identified as George Floyd, can be heard to shout “I cannot breathe” and “Don’t kill me!” He then grows motionless, eyes closed, face-first on the road. The incident was condemned by political leaders and social justice advocates. “For five minutes we watched as a white officer pressed his knee to the neck of a black man,” Jacob Frey, the Minneapolis mayor, said in a press conference. “For five minutes. This officer failed in the most basic human sense. “[Floyd] should not have died,” Frey added, apologizing to the family and the black community in Minneapolis. The incident happened late on Monday, when officers responded to a call from a grocery store that claimed Floyd had used a forged check. When located in his car, police said, he “physically resisted officers” while possibly under the influence of drugs or alcohol. Floyd was believed to be in his forties. In a press conference on Tuesday, the Minneapolis police department confirmed he “died a short time” after a “medical incident”, after being transported to hospital. “[They] were able to get the suspect into handcuffs and realized that the suspect was suffering a medical distress,” a spokesman said, saying officers “called for an ambulance”. In the video footage, witnesses can be heard shouting at officers to get off Floyd’s neck. One yells: “Bro, he’s not even fucking moving!” Another asks if “you’re going to just sit there with your knee on his neck?” Another witness says: “Did you kill him?” On Tuesday afternoon, Frey announced that four police officers had been fired. In a Facebook video, witness Darnella Frazier said she stopped to record the incident as she was on her way to meet friends. Officers had already pinned Floyd to the ground, she said, when one began kneeling on him. “They was pinning him down by his neck and he was crying. They wasn’t trying to take him serious,” she said. “The police killed him, bro, right in front of everybody.” Floyd’s family retained the prominent civil rights attorney Benjamin Crump, who in a statement said his death was the result of “abusive, excessive and inhumane use of force”. “We will seek justice for the family of George Floyd, as we demand answers from the Minnesota police department,” Crump said. “How many ‘while black’ deaths will it take until the racial profiling and undervaluing of black lives by police finally ends?” Outrage continued to grow on Tuesday, locally and online. The mayor of St Paul, Melvin Carter, called the footage of “a defenseless, handcuffed man one of the most vile and heartbreaking images” he had ever seen. Law enforcement officials in Minnesota have come under fire in recent years. Protests erupted in the state in 2016, after 32-year-old Philando Castile, who was black, was shot and killed by a St Anthony police officer during a traffic stop. Footage of the incident also went viral online. The officer, Jeronimo Yanez, who is Latino, was acquitted of a second-degree manslaughter charge and two counts of dangerous discharge of a firearm. On Tuesday, the Minneapolis city council member Andrea Jenkins said in a statement the community “must demand answers” as it “continues to be traumatized again, and again and again”. The Democratic Minnesota senator Amy Klobuchar demanded “a complete and thorough outside investigation”, saying in a statement: “Those involved in this incident must be held accountable.” Klobuchar, a former 2020 presidential candidate, has faced criticism for not prosecuting controversial police killings of black people when she was a county district attorney. Body camera footage was turned over to the Minnesota Bureau of Criminal Apprehension (MBCA). The MBCA said the officers’ names will be released after initial interviews with the people involved and witnesses. It also confirmed FBI officials were conducting a separate federal civil rights investigation, at the request of Minneapolis police. The MBCA did not immediately respond to a request for comment.