SAN DIEGO (CNS) - Construction workers were evacuated from the federal courthouse in downtown San Diego Monday when smoke was spotted near a ceiling, according to a dispatcher with the San Diego Fire-Rescue Department.

Firefighters were sent to the U.S. District Courthouse at 940 Front St. about 1:30 p.m., the dispatcher said. The courthouse was closed to the public Monday because of Martin Luther King Day.

Firefighters who responded to the building reported smelling an odor but, after about a half-hour of searching the five-story building floor-by-floor, they hadn't located the source of the problem, the dispatcher said.