Police investigate after an attempted armed robbery at a CVS, 1539 Clavey Road in Highland Park early Sunday morning | Photo: Joe Davis.

Employees of a CVS store in Highland Park are being credited for thwarting an armed robbery after they set off the fire alarms early Sunday morning, police said.

The Highland Park Police Department and Highland Park Fire Department responded around 3 a.m. Sunday to the CVS drug store, 1539 Clavey Road, which is just west of Route 41.

Highland Park Deputy Police Chief Jonathan Lowman said that two men entered the store and one of them displayed a gun.

Police investigate after an attempted armed robbery at a CVS, 1539 Clavey Road in Highland Park early Sunday morning | Photo: Joe Davis.

The employees quickly left the building through a rear door and intentionally activated the fire alarm, Lowman said. After the fire alarm began sounding, the two suspects left the store without taking anything.

Police arrived and surrounded the building. A SWAT team from the Northern Illinois Police Alarm System was called to the scene to search the building in order to make sure the offenders were not inside, Lowman said.

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Witnesses reported seeing dozens of police officers arrive at the scene from as far as Streamwood. The scene remained active until around 9 a.m. Sunday, more than six hours after the initial call.

The robbery remains under investigation by the Highland Park Police Department.