12/30/2011 10:33 am ET

Clifton Lewis, Off-Duty Chicago Police Officer, Fatally Shot During Grocery Store Robbery (VIDEO)

An off-duty Chicago Police officer was killed Thursday night while working security at a West Side grocery store.

According to NBC Chicago, Clifton Lewis was trying to stop a robbery at M&M Quick Foods when he was shot. The incident occurred about 8:30 p.m. in the 1200 block of North Austin Street.

Lewis, 41, was an eight year veteran of the department who worked in the 15th District, the Chicago Sun-Times reports. He was shot multiple times, and police told the paper they have not been able to find his gun.

Store owner Jaimini Patel told the Chicago Tribune that the store was robbed about three weeks ago, which is reportedly why Lewis was hired about one week ago.

"For so many years, nothing happened like this," she told the Tribune. "Not like this, a shooting, somebody dying. Never happened. I don't know what to say now."

Witnesses told the Sun-Times they heard the guard shouting at another man in the store, and they left promptly, fearing for their safety.

The gunman reportedly had "gang tattoos on his face," one witness told the Tribune.

"Shocking, it's shocking," one area resident told the Tribune about the shooting. He and his son had reportedly spoken with the officer earlier Thursday evening.

Police are questioning two people who were pulled over near North Laramie Avenue and West Hirsch Street, NBC Chicago reports. The vehicle may have been used as a getaway car in the shooting.

Hundreds of officers gathered at the crime scene early Friday, after a salute by officers and firefighters at the Cook County Medical Examiner's office overnight. Chicago Police Supt. Garry McCarthy has yet to comment on the slaying.

Lewis was not the only gunshot victim during a violent night in Chicago. NBC Chicago reports:

Another man was killed in the 1500 block of South Kedzie. Police said he was shot in the head.

Six other people, including three teens, were shot in other incidents around the city. No one is in custody in any of the cases.