An inspection revealed mercury vapor, asbestos dust, and lead paint throughout the building.
The San Francisco Chronicle reports that university officials are now scrambling to figure out where to put more than 2,500 students and staff who use the building.
The university has posted information about the closure online.
In a message to faculty and staff, SFSU President Les Wong says, "Contingency teams are attempting to relocate classes, offices and laboratories assigned to the building. As new classroom locations are identified, they are being entered into the class schedule."
The semester begins on Monday.