A bank robbery in Anne Arundel County on Monday was at least the 11th robbery or attempted robbery at a financial institution in the Washington area in 11 days.

Monday’s robbery occurred in the Odenton area and was carried out by three men who drew handguns and demanded money, the county police said.

The robbers entered the Old Line bank in the 1100 block of Annapolis Road shortly after 10 a.m. and fled with an undetermined amount of cash, the police said.

Several employees and customers were in the bank at the time, but none was injured, the police said.

The robbery was the latest in a series that began Dec. 20 in the Hayfield area of Fairfax County. As in the Odenton incident, the robbers in the Hayfield holdup were armed. A robbery in Laurel on Dec. 21 also involved a weapon.

In that incident, a shot was fired but no injuries were reported. The robber’s disguise was distinctive, and was described as a beard reminiscent of Santa Claus or of a character on the “Duck Dynasty” television show.

In the majority of the incidents, no weapon was shown and demands were made orally or through a note.

Surveillance cameras are in use at banks, and the robbers have generally tried to disguise their appearance by wearing hats or by wrapping scarves around their faces.

In the Odenton holdup, police said the robbers’ faces were concealed by clothing.

In a robbery that occurred in Alexandria on Saturday at the M&T bank branch in the 800 block of South Washington Street, the robber wore a gray hooded sweatshirt and sunglasses, the Alexandria police said.

As in most of the other incidents, the robber made his demands in a note, which the police said he handed to a teller.

The day before, a woman wearing a pink or red scarf that covered almost all of her head robbed a Capital One Bank branch in the 5800 block of Eastern Avenue in Prince George’s County. Police said the same woman held up a Capital One branch Dec. 2 in the 6200 block of Annapolis Road.

The only robber to be rebuffed was the man who tried to get cash on Friday from a Citibank branch in Columbia Heights in the District. Like several of the other robbers, he passed a note to a teller, but the teller did not provide any money, and the man left.

In a compilation of bank robbery figures, the FBI said a total of 5,546 federally insured financial institutions had been holdup targets throughout the United States in 2010.

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