A maintenance building at the San Francisco Airport was evacuated after a fire broke out there early Wednesday morning, an airport spokesperson confirmed.

The fire was first reported at 7:30 a.m. and has since been extinguished, according fire department officials. No injuries have been reported.

Fire officials announced on Twitter that the fire was contained at about 8:20 a.m. and that appears to have started accidentally in a heating and air conditioning unit on the roof.

After San Francisco fire fighters and mutual aid responders extinguished the fire, the building, located north of the airport’s terminals, was deemed safe for employees to re-enter, said SFO Spokesperson Doug Yakel.

Passenger terminals were not affected by the fire, and all flights remain operating normally.

lwaxmann@sfexaminer.com