CHICAGO (CBS) – A man delivering an oxygen tank is dead after the tank reportedly fell onto him after he suffered an apparent heart attack Tuesday afternoon on the South Side.

Police responded at 2:24 p.m. to the 9000 block of South Western Avenue and discovered a man apparently delivering an oxygen tank appeared to have suffered a heart attack, police said, citing preliminary information.

But a Cook County Medical Examiner’s office spokesman indicated the man died after an oxygen tank fell onto him.

Gary Matras, 61, of W. Touhy Ave. in Des Plaines, was taken to Advocate Christ Medical Center in Oak Lawn and pronounced dead 3:06 p.m., the medical examiner’s office said.

Police are conducting a “death investigation” pending the results of a Wednesday autopsy.

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