CLEVELAND, Ohio -- An off-duty police officer shot and killed a man late Saturday at the Corner Alley bowling alley in Cleveland's University Circle neighborhood, according to Commander James McPike, who oversees the department homicide unit.

The shooting happened about 11 p.m. Saturday at the bowling alley on Euclid Avenue and Ford Drive, according to three police sources.

A fight broke out inside the bar and the off-duty police officer, who was working part-time security at the business, escorted several men outside after they were kicked out, according to police.

One of the men, a 21-year-old, came back to the bowling alley and attacked the officer several feet from the front door, police said.

Police said the officer fired shots at the man. A witness said he heard two gunshots. The man was taken to University Hospitals, where he died, according to police.

The officer also suffered injuries and was taken to a hospital for treatment, Cleveland police spokeswoman Sgt. Jennifer Ciaccia said. No one else was injured.

Cleveland, University Circle and Case Western police officers surrounded the area following the shooting.

Crime scene investigators marked evidence, including at least one bullet casing and a pool of blood, just steps outside the front door of the popular nightspot.

A video taken by a witness and reviewed by cleveland.com showed what appears to be an officer, surrounded by several bar employees, trying to give emergency medical treatment to the man.

Officers and detectives were inside the bowling alley interviewing witnesses. Several other witnesses were ordered to remain at the scene until they could be interviewed

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Cleveland Police Chief Calvin Williams showed up to the scene, and left after refusing to answer questions from a reporter.