Portland Police are asking for the public's help as they investigate the sixth armed robbery of a local business in a week.

The robbery happened Sunday night at the China Taste Restaurant, 1223 Washington Avenue, in Portland. Police said in a media release that a gunman entered the restaurant just after 8:30, brandished a black semi-automatic handgun, and demanded cash from the clerk. The suspect fled, before receiving any cash, when other employees entered the room from the kitchen.

A South Portland Police canine attempted to track the suspect, but the trail ended on Maine Avenue. Officials say the man likely got into a vehicle at that point. He's described as being a white man, about 5'5" tall, wearing an oversized hooded sweatshirt, with a dark green and light green camo pattern jacket, with the hood pulled up on his head. He was also wearing a dark-colored zip-up shirt that was pulled up to cover part of his face.

Officials say this is the 6th robbery since March 20th in the Greater Portland area, including Westbrook, Portland, Falmouth, and Cumberland. In each case, a suspect fitting a similar description, enters the business with a handgun and demands money. Investigators are now working to determine if they're looking for a single suspect. The photo (above) is from a robbery on March 20th at the Riverton Gas Station on Forest Avenue, which is one of the six currently being investigated as possibly being connected.

Police are asking residents in the area of Washington Avenue and Maine Avenue to check video from their home surveillance systems to see if any vehicle or pedestrian traffic was recorded around the time of the robbery. Anyone who thinks they may have information is encouraged to call the Portland Police Department at (207) 874-8575.