Four people were injured Saturday after a flash fire broke out in the ductwork of the State Department building in Washington, fire officials said.

One person was in a "life-threatening condition" and two others were in serious but non-life threatening condition at Washington Hospital Center, authorities said. The fourth person fell from a ladder and hurt his knee.

The fire broke out after 11 a.m., as construction crews were working on the premises, and was extinguished on short order, said Lon Walls, a spokesman for Washington's fire department.