WASHINGTON – Police in the District and Montgomery County are investigating a rash of armed robberies of convenience stores and pharmacies.

Montgomery County police think the four armed robberies in the county are related.

They happened in October and November either late at night or during overnight hours.

Two 7-Elevens were targeted, one on Oct. 12 in the 19000 block of Watkins Mill Road, the other on Oct. 27 in the 9000 block of Snouffer School Road. A CVS in the 19000 block of Montgomery Village Avenue was robbed twice, on Nov. 17 and Nov. 30.

In each case, a man with a sawed-off shotgun entered the store with his own bag for the clerk to stuff with cash.

Police are looking for two suspects in connection with these cases.

The suspect in the Oct. 27 robbery is described as a male with a light-complexion about 5’8″ tall.

The robber in the other cases is described as a black man, 25 to 30 years old, 6′ to 6’2″ tall and 160 to 180 pounds.

Before the Oct. 27 holdup, two people wearing masks were seen outside the store, so police think they may be working together.

Police have released video of the robbery at the 7-Eleven on Oct. 12:

In the District, there were four holdups at convenience stores in just two days. The same 7-11 on Benning Road, NE was held up two times in two days.

“A group of three or four gentlemen running around the city that are hitting these commercial establishments, armed with guns,” says D.C. Police Chief Cathy Lanier on WTOP’s Ask the Chief.

All four robberies involved two or three armed gunmen entering the store late at night or early in the morning. The men would enter the store and demand that the cashier empty the cash register. The men fled from three of the robberies in a dark-colored vehicle.

D.C. Police have released videos of the four robberies.

Video of the robbery at the 7-Eleven at 950 Division Avenue, NE on Nov. 27, 2011:

Video of the robbery at the 7-Eleven at 2501 Benning Road, NE on Nov. 27, 2011:

Video of the robbery at the 7-Eleven at 2501 Benning Road, NE on Nov. 28, 2011

Video of the robbery of Shop Express at 3900 Benning Road, NE on Nov. 28, 2011

Anyone with information about the robberies in Montgomery County are asked to call 240-773-5100. Those who wish to remain anonymous may call Crime Solvers of Montgomery County toll-free at 1-866-411-TIPS (8477).

Anyone with information about robberies in D.C. Are asked to call 202-727-9099 or 1-888-919-CRIM[E] (2746).

WTOP’s Michelle Basch and Dick Uliano contributed to this report. Follow Michelle and WTOP on Twitter.

(Copyright 2011 by WTOP. All Rights Reserved.)