Masked gunmen armed with assault rifles fatally shot a guard today during a robbery of an armored truck at a bank in Hyattsville, Md., before escaping in a stolen car, authorities said.

The guard, who was reported to have been shot at least twice in the upper body and once in the face, was rushed to a hospital, where he underwent surgery, Prince George's County police said. Police said the guard subsequently died.

The guard was employed by the Maryland-based Dunbar company, which uses armored vehicles to transport cash and other valuables.

The robbery occurred after 1 p.m. today at the BB&T bank in the 3500 block of Hamilton Street in Hyattsville just northeast of Washington, D.C., as the red Dunbar armored truck was making a pickup, police said.

They said two gunmen dressed all in black, with masks and body armor, used assault weapons in the robbery.

Police Lt. Philip Yuen said the robbers took at least one bag of money, but that he did not know the amount that was stolen.

The driver of the armored truck hit the robbers' SUV and blocked it, causing them to flee on foot to the rear of the bank, Yuen said. There, the men commandeered a woman's car and escaped.

The suspects were spotted fleeing in the carjacked vehicle, a silver Pontiac Grand Prix with a spoiler and the Maryland license plate HYT-076, police said. One of the men might have injured a leg in the heist, they said.

Investigators cordoned off the scene of the robbery on a street in a residential neighborhood and searched for clues into the late afternoon.

A gang of robbers using similar equipment hit six banks in Washington and suburban Maryland earlier this year. Seven men have been arrested and indicted in those robberies, but police said one suspect was still at large.

The serial bank robberies took place between January and June. The targets included four banks in the District and two in Maryland, one of them in Hyattsville.

Washington Post staff writer Jamie Stockwell contributed to this report.