An armed man killed by Chicago police was shot as he reached towards his waist, footage from an officer’s body-worn camera shows.

Police Superintendent Eddie Johnson said the video was released because he hoped to dispel rumours that Harith Augustus, 37, was unarmed.

He also hoped that making the 30-second clip public would prevent another violent confrontation between residents and officers.

Protesters angry about the killing took to the streets on Saturday amid unrest in the city over police shootings, particularly against black men and other minorities.

Some threw rocks and bottles, including some filled with urine, at officers and police pulled people to the ground and hit them with batons.

“The community needs some answers and they need them now,” Mr Johnson told reporters. “We can’t have another night like last night.”

He said Augustus’ family was in favour of releasing the video for the same reason.

Four protesters were arrested in the clash, and some police officers suffered minor injuries. Two police cars were also damaged.

A protest and march after the video’s release was calmer, with some demonstrators holding a moment of silence for Augustus, the Chicago Sun-Times reported.

Still image from the video released by police
The video zooms in on the holster (Chicago Police Department via AP)

It is not fully clear why officers initially approached Augustus. On Saturday, patrol chief Fred Waller said officers patrolling on foot tried to question him over a “bulge around his waistband” that suggested he was armed.

The video, which lacks sound, shows four officers approaching Augustus outside a shop on the city’s South Side. An officer points to Augustus’ waist and he backs away. Three officers try to grab his arms and he tries to get away, backing into a police cruiser as his shirt flies up, showing the gun.

The footage pauses and zooms in on the weapon, which police spokesman Anthony Guglielmi said was done to ensure a semi-automatic handgun in its holster and two bullet magazines tucked into Augustus’ waist could be seen clearly.

Augustus then runs away and into the street as a police vehicle drives up. He spins and darts between two police cars as he reaches toward his waist.

Augustus did not fire his weapon and the footage does not show him pulling the gun out of its holster.

Police also released a 50-second slow-motion clip showing Augustus reaching toward his waist. It is not clear if he was going for the weapon.

Mr Guglielmi said Augustus did appear to try to grab something at his waist.

Medical examiners said Augustus died of multiple gunshot wounds.

Augustus had no recent arrest history, Mr Guglielmi said. He had a valid firearm owners’ identification card but detectives have found no documentation that he had a permit to carry a concealed weapon, Mr Johnson said.