The air traffic control tower at Baltimore-Washington International Thurgood Marshall Airport was evacuated briefly after the fire alarm went off.
The airport's fire department responded to a report of a fire alarm at the tower about 6:45 a.m. Tuesday, airport spokesman Jonathan Dean said in an email. Firefighters didn't find smoke or fire.
Tower functions were suspended briefly, but personnel returned to work about 15 minutes later.
Dean said he didn't know how many flights were delayed, but he said the overall effect was minor. He says the cause of the alarm is being investigated.