SAN FRANCISCO -- Two adults and two children who were trapped in a San Francisco home during a three-alarm fire late Saturday night escaped the deadly flames by jumping out a window, authorities said.

The fire at 71 Cuvier St. near Bosworth Street was reported at about 10:55 p.m. The home lost power during the fire, and the two adults and two children inside had to escape out a window, according to Lt. Ken Smith.

No injuries were reported from the fire, but Smith said the incident was a reminder that people should have power outage and escape plans in case of an emergency.

"They were pretty lucky to get out of there," he said.

The residents were displaced by the fire and aided by the American Red Cross, Smith said.

The blaze also spread to the residential building next door at 77 Cuvier St., Smith said. The building sustained damage to the walls, and the residents were able to exit regularly.

The blaze was controlled at 11:43 p.m., Smith said. Initial reports that the fire was controlled earlier were mistaken, he said, as firefighters were still working on the blaze.

Investigators have not determined how the fire started, Smith said.