The two-alarm blaze was reported at 1:28 a.m. at 925 Montgomery St. near Pacific Street, a fire dispatcher said.
At least a couple of people, including a firefighter, were injured by the fire, Red Cross spokesman Jim Mallory said. Fire officials were not immediately available to provide more details about the injuries.
The blaze has since been controlled, but firefighters remained at the building as of noontime to make sure the fire doesn't reignite, the dispatcher said.
The Bay Area chapter of the Red Cross opened a temporary evacuation center this morning at a dance studio at 435 Broadway for residents displaced by the fire, and have since opened a shelter, Mallory said.
About 45 residents from the building checked into the evacuation center, and about 30 have been taken to the shelter, located at the South of Market Recreation Center at 270 Sixth St, Mallory said.
It is unclear when the residents will be able to return to their homes, he said.
Any residents affected by the fire can call the Red Cross at (888) 4-HELP-BAY.
