Police are dealing with a rash of armed robberies in Dorchester, with two crews of men believed to be behind five convenience store robberies since Tuesday.

“We believe these are professional crews hitting Dorchester,” said C-11 commander Captain Tim Connolly on Friday morning. “We believe they’ve worked in other areas.”

The spree began in the Ashmont area at about 11 p.m. on Tuesday, Jan. 9, when two men held up the Ashmont Market at 630 Adams St. at gunpoint. They entered the store with firearms and demanded money, police said, walking off with about $1,200.

Both men are described as white or Hispanic of unknown age, average height, average build. One of the suspects had distinctive tattoos on both of his hands.

Another robbery occurred the next night at Rosario's Grocery, located at 760 Washington St. Two armed suspects entered the store at about 11:36 p.m. One man pointed a gun at one of the store employees while a second suspect walked around the counter and emptied the cash register.

Upon exiting the store, both suspects were seen running along Ashmont Street towards Dorchester Avenue.

Three similar robberies took place around the 1700 and 1800 block of Dorchester Avenue on Thursday night, Connolly said.

One armed man robbed 1886 Dorchester Ave. -- a 7-11 -- at about 5:30 p.m. A group of three black men robbed the Gibbs gas station at 1707 Dorchester Ave. at 7:39 p.m. and patrons of Ann's Coin Laundry at 1828 Dorchester Ave. at 7:52 p.m.

Undercover officers are in the area, Connolly said, reminding store owners to lock their doors and alert police if they see anything suspicious.

“Remain vigilant,” he said. “If something looks out of the ordinary, don’t be afraid to call us. We’d rather go somewhere and have it not be a robbery than get there after one.”

For now, police believe the crimes are the work of two crews, one more organized than the other. In the course of one robbery, a suspect accidentally discharged his weapon, shooting a cash register. No one has been injured during the armed robberies. The suspects sometimes wore masks or hooded sweatshirts.

The police department is actively reviewing the facts and circumstances surrounding these incidents. Anyone with information is asked to call detectives assigned to District C-11 at (617) 343-4335.