Suspect barricades himself inside Census Bureau headquarters after shooting security guard
Crime scene (AFP)

A gunman is believed to have barricaded himself inside the U.S. Census Bureau headquarters in Maryland after shooting a security guard at one of the outside gates on Thursday evening, a fire official said.

Emergency personnel were called to the scene in Suitland, Maryland, about 10 miles from Washington, D.C., at about 6:30 p.m. The guard was shot in the upper body and taken to a local hospital in "extremely critical condition," said Mark Brady, spokesman for the Prince George's County Fire Department.

Brady said he did not know if the guard, an adult male, was a federal employee or a contractor.

A representative for Prince George's County Police was not immediately available for comment.

In a statement on its Twitter account, the Census Bureau said that there had been an "incident" at the Suitland Federal Center and there was an ongoing investigation.

"We are committed to the safety of all staff who work at the Census Bureau and are currently making sure that everyone is safe and secure," the statement said.

(Reporting by Mary Wisniewski in Chicago; Editing by Eric Beech and Eric Walsh)