Updated

Workers and visitors at the Library of Congress have been allowed back into its Madison Building after smoke prompted a brief evacuation.

D.C. fire department spokesman Pete Piringer says smoke was initially reported Wednesday afternoon in the sixth floor of that library building located on Capitol Hill. A burning odor also was reported on other floors. Piringer says firefighters traced the smoke to a malfunctioning air handler.

A library spokesman says the building had to be evacuated for nearly an hour.

No injuries were reported.

The building serves as a memorial to a past president, James Madison. It is one of the three largest buildings in the Washington area after the Pentagon and FBI buildings and houses vast amounts of research materials.