Police in the US city of Chicago have released a new video showing officers chasing an African American teenager who was fatally shot following a reported car theft, igniting fears of a new wave of protests over police using lethal force against black people.

In the video released on Friday, several officers are seen pursuing 18-year-old Paul O'Neal through a back garden and over a fence in a residential neighbourhood while several shots ring out.

Officers are then seen handcuffing O'Neal, who is face down on the ground with blood on the back of his white shirt. One police officer is overheard in the video cursing the wounded teenager, and telling him "to put your hands behind your back".

No one is seen immediately administering first aid to the teenager. A minute after putting the suspect in handcuffs, the officers mention calling an ambulance.  

It was not clear in the video if the teenager was armed, but one officer is heard saying "f**k you shoot at us".

One of the officers is also overheard in the video asking another officer, "They [sic] shot at us too, right?" 

The fatal shot is not shown in the video and police are investigating why the body camera of the officer who fired the bullet was not turned on, or if it malfunctioned. 

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"Please bear in mind that this video material, as shocking and disturbing as it is, is not the only evidence to be gathered and analysed," said Sharon Fairley, an investigator of the incident.

Michael Oppenheimer, a lawyer for O'Neal's family, described the shooting as "one of the most horrific things" he had seen, in a news conference. 

He accused the police of carrying out the "execution" of a "loving son".

The video from July 28 was made public by the agency that investigates Chicago police misconduct.

It was the first time the city has made a video of a fatal police shooting public following adoption of a new policy that calls for the police to do so within 60 days.

The new transparency is an attempt to restore public confidence in the police department after video released last year showed Laquan McDonald, a black teenager, being shot 16 times by a white officer. The killing sparked protests and led to the dismissal of the police superintendent.

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Al Jazeera's Alan Fisher, reporting from Washington DC, said that three police officers involved in the shooting of O'Neal now face the "prospect of being fired", and have been relieved of all police powers pending an investigation into the shooting.

Fisher said the swift release of the video demonstrated that the Chicago police department is adopting a new approach to address allegations of racial bias.

"By taking this prompt action, the police are hoping obviously to show that they are doing things differently now, and hoping that that will keep protesters off the streets," he said.

Source: Al Jazeera and agencies