A team of firefighters was spending the early hours Thursday dealing with any hot spots left in a San Francisco apartment fire that left as many as 60 people homeless, fire officials said. The five-alarm blaze engulfed three buildings before 150 firefighters, or about half the department’s daytime firefighting force, brought it under control after a near three-hour battle, Fire Chief Joanne Hayes-White said Thursday. Fire investigators will try to determine Friday what sparked the blaze, officials said.