Police in Scarborough, South Portland and Westbrook are investigating a string of robberies reported in the past several weeks.

Since early June, police have responded to a half-dozen robberies at pharmacies, stores and a sandwich shop. The three departments are jointly investigating the robberies based on similarities, including suspect descriptions, said Scarborough Detective Sgt. Rick Rouse.

The latest robbery was reported to Scarborough police at 4:30 p.m. Tuesday. Police say a masked man robbed the Pet Smart store on Gallery Boulevard. He demanded money and made reference to a gun, but did not display a weapon, according to police.

The suspect, who was wearing a blue face mask and black hat, was last seen leaving the area in a black Dodge pickup truck with temporary plates.

Scarborough police say a Subway shop on Payne Road was also robbed this month. And on June 20, a man robbed the Marden’s store on Payne Road of an undisclosed amount of cash. That suspect had a white cloth draped over his head, police said.

In Westbrook, police are investigating a June 12 robbery at CVS on Main Street. A suspect wearing a blue face mask, black hat and sunglasses did not display a weapon and ran from the area.

Two pharmacies in South Portland were robbed within a short time on June 14. That afternoon, a man entered the Walgreens on Main Street, said he had a firearm and demanded cash from an employee, police said. The suspect did not show a weapon and left with an unknown amount of cash.

While officers were responding to the Walgreens robbery, another robbery was reported at the CVS pharmacy on Market Street. Police say a man also entered that store, said he had a gun but didn’t display one, and ran away with cash. No one was injured during the South Portland robberies.

South Portland police say they believe the pharmacy robberies in the city are related and released security video showing a suspect wearing a blue hat, sunglasses and black face covering.