Police are on the hunt for a gunman who they say chased a man inside a North Philly grocery store before shooting and killing him execution-style.

Investigators say the masked gunman followed a 21-year-old man inside the My City Supermarket on 19th Street and Susquehanna Avenue just before 5 p.m. Once inside, the gunman allegedly fired 13 shots from a semi-automatic handgun at the man.

The man, later identified as Kontue Johnson, was struck several times and collapsed to the floor in one of the aisles.

"When the victim collapsed in one of the aisles inside the store, based on witness accounts, this individual stood over him and shot him execution style," said Philadelphia Police Chief Inspector Scott Small.

Johnson, who hailed from just two blocks from he was shot, was taken to Temple University Hospital where he died a short time later.

Police say the shooting stemmed from an argument. Investigators reviewed surveillance video from the scene in hopes of zeroing in on the triggerman.

Anyone with information is asked to contact Philadelphia Police.