A two-alarm fire last night at a National Security Agency building at Fort Meade in Anne Arundel County prompted the evacuation of an undisclosed number of employees.

No injuries were reported, said Patricia Jensen, a spokeswoman for the top-secret agency.

Jensen said the fire was reported about 7 p.m. in an operations building. She declined to specify the size or type of the building, or to describe the work carried on there.

Four engines and one aerial tower from the Fort Meade Fire Department brought the fire under control quickly. The cause of the fire was being investigated.