PORTLAND — Portland police are investigating an armed robbery that took place tonight at a Brighton Avenue convenience store.

Lt. Gary Hutcheson said a male suspect, who was wearing a black ski mask over his face, entered the XtraMart convenience store, 865 Brighton Avenue, around 9:30 p.m.

The robber displayed a handgun and threatened the store clerk, who handed over an undetermined amount of cash.

Hutcheson said police used a dog to track the suspect, who initially fled on foot, but is believed to have escaped in a car that may have been waiting nearby.

The suspect was wearing a black hooded sweatshirt with faded jeans.