According to a spokesman for the D.C. Metropolitan Police Department, the gunman entered lobby of the building in downtown Washington at 10:45 a.m. Wednesday morning, was confronted by the security guard and opened fire.
The guard was shot in the left arm, police said. The suspected gunman was tackled and then taken into custody.
"As far as I'm concerned, the security officer here is a hero," Metro Police chief Cathy Lanier said.