A Pittsfield man was arrested Monday in connection with a string of five convenience store robberies in just over 12 hours in Pittsfield and Lenox.

Patrick Sheerin, 28, is facing five counts of armed robbery in the spree, which ran from Sunday evening through Monday morning. He is expected to be arraigned Tuesday in Central Berkshire District Court.

The first three robberies took place over the span of 25 minutes, according to a statement released Monday afternoon by Pittsfield Police. Sheerin allegedly demanded cash from the businesses and said he had a weapon, although none was shown at any of the robberies.

Sheerin allegedly began by robbing the Lipton Mart on South Street in Pittsfield at 6:51 p.m. Sunday, police said. About 7:04 p.m., Lenox Police responded to a report of the robbery in progress at the Lipton Mart on Pittsfield Road near the junction with Holmes Road, according to Chief Stephen E. O’Brien.

The clerk told police that the man had pushed a note under the protective screen, seeking a list of items.

“The clerk, who was obviously stunned, stated that the suspect declared, ’This is an armed robbery, and I have a gun,’ ” O’Brien said.

While en route, police were informed via dispatch that the store clerk was in phone contact, locked within a secure area, and reported that the man was trying to force open the cash register.

He fled in a silver sedan before police arrived. A canine from the state police tracked the man from the store to the parking lot, O’Brien said.

By 7:16 p.m., an armed robbery was reported at Palmer’s Variety on Elm Street in Pittsfield, at the other end of Holmes Road, police said.

Hours later, Sheerin allegedly hit the Cumberland Farms on Dalton Avenue, and, at 8:29 a.m., the Convenience Plus on Dalton Avenue.

Police said they suspected that one person was responsible for all five robberies, and later Tuesday morning, police released a screenshot captured on surveillance video at the Lenox store.

Sheerin later was arrested without incident.

The investigation is being conducted by the Pittsfield, Lenox and state police. Other charges might be forthcoming.

Lenox Police also are investigating an unrelated incident Saturday in which three men dressed in black wearing black masks forced their way into a room at the Wagon Wheel motel on Pittsfield Road, allegedly brandishing a handgun, and ransacked the premises.

The three motel guests, all from Springfield, said they didn’t know the suspects and were unable to identify them, O’Brien said.

The suspects fled in a black Mitsubishi pickup truck without anything taken from the motel room, he said. A witness said that he heard the disturbance and saw the truck leaving at high speed, heading north.

O’Brien said there have been a series of crimes at motels on Pittsfield Road in the commercial corridor between Holmes Road and the Pittsfield city line in the northern sector of Lenox.

“These have become quite taxing to our resources,” said O’Brien, who has asked state police from the Lee barracks to increase patrols in the area.

“We are spending a lot of time monitoring what is going on in the commercial corridor in the north end of town,” he stated. “Some hotels are doing better than others at not attracting our attention.”

In connection with a series of shoplifting incidents at Price Chopper’s Market 32, he noted that the store’s loss-prevention team “does terrific work.”

Police have increased patrols in Lenox and Pittsfield and are asking all business owners and employees to be aware of any suspicious people.

“If your business is equipped with a video surveillance system or alarm, please ensure that they are operational,” the release from Pittsfield Police stated.

O’Brien urged anyone with information on either of the two weekend incidents to contact Lenox Police at 413-637-2346.

Anyone with information about the Pittsfield robberies or other suspicious activity is asked to call lead detective James Losaw at 413-448-9700, ext. 572.