US police have shot and killed a black security officer after he tackled a suspected shooter while working at a bar.

Police were responding to reports of a shooting at Manny’s Luxury Lounge in Robbins Illinois early on Sunday morning.

Witnesses said shots were fired after a fight broke out and, as police arrived; 26-year-old Jemel Roberson was holding someone on the ground at gunpoint with a knee in his back.

Mr Roberson was wearing clothes reading ‘Security’ and witnesses said people in the crowd had shouted at the arriving police that he was a guard.

Sophia Ansari, a spokeswoman for the Cook County Sheriff’s Office, said an officer with the Midlothian Police Department shot Mr. Roberson.

She said he later died in hospital.

Shooting

She said a total of five people were shot during the incident, with four people – including the man suspected of initially opening fire – sustaining non-life threatening injuries.

Ms Ansari said the man who initially opened fire was still in hospital and had not been charged.

Midlothian police chief, Dan Delaney, confirmed in a statement that one of his officers had shot a “subject with a gun.”

The officer was not named.

Lawsuit

On Monday, Mr Roberson’s mother filed a federal lawsuit against the police officer and the village of Midlothian.

The suit argues that the shooting was unprovoked, unjustified, excessive and unreasonable.

Mr Roberson, who reportedly worked as an organist at several local churches held a state firearm owner’s ID card, authorising him to carry a gun.