An off-duty Chicago police officer working at a convenience store on Austin Boulevard was shot and killed Thursday night when armed offenders tried to rob the store, according to a statement from Chicago Police News Affairs.

Officer Clifton Lewis, 41, was working security at M & M Foods, 1201 N. Austin Blvd., when the offenders entered the store around 8:30 p.m., the statement said.

One offender fired several shots, striking Lewis, an 8-year veteran of the department. Lewis was taken to Stroger Hospital, where he died. Police did not say how many offenders were involved.

The offenders fled the scene. No one is in custody and the matter is still under investigation.

Chicago Mayor Rahm Emanuel released a statement Friday afternoon calling Lewis’ death a “tragic and senseless loss” for his family, his colleagues and for the city of Chicago.

“Officer Lewis died as he had lived, serving and protecting his community. . .His courage and sense of duty to the City are examples for us all.”