PHILADELPHIA (CBS) — A convenience store clerk is hospitalized after being shot during a robbery in Philadelphia early Monday morning.

The incident happened at about 1 a.m. at the Hess Gas station located at Island and Elmwood Avenues in Southwest Philadelphia.

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According to investigators, the three suspects gained access to the store by posing as delivery men.

An 18-year-old store employee noticed the robbery in progress and hid in a men’s bathroom. The suspects eventually found the employee, tied him up and shot him one time in the head.

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The employee was taken to the Hospital of the University of Pennsylvania where he is listed in stable condition.

The suspects fled the store, but it was not immediately known if anything was taken.

Investigators believe Monday morning’s robbery may be connected to a similar robbery at another Hess Gas station on Passyunk Avenue Saturday night.

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Both robberies remain under investigation.