PITTSFIELD — Police are investigating an armed robbery of the Big Y Express on Sunday night.

Shortly before 11:30 p.m., a man entered the store on West Street, displayed a handgun, and demanded money, according to a news release by the Pittsfield Police Department. The suspect then fled with an undisclosed amount of cash.

The two clerks working at the time were not injured.

Police officers, including a K9 unit, responded immediately, followed by members of the detective and crime scene units, and the Massachusetts State Police.

The suspect is described as a white male, approximately 5 feet, 7 inches tall, with medium build. He was wearing grey sweatpants and a grey sweatshirt, and an additional piece of purple and yellow outerwear covering his face.

The incident remains under investigation. Anyone with information is encouraged to contact the detective bureau at 413-448-9705.