Crews continued to work this morning to secure a building where an explosion occurred Monday night so that investigators can enter and determine the cause of the blast, a San Francisco police sergeant said.
The explosion happened around 7:45 p.m. in the front part of a two-story, wood-frame home at 108 Congo St.
San Francisco police Sgt. Wilfred Williams said the Police Department is leading the investigation but that fire crews, building inspectors, Pacific Gas and Electric Co. and the Bureau of Alcohol, Tobacco, Firearms and Explosives have also responded.
Three males and an elderly woman were in the house at the time of the explosion and were taken to a hospital for treatment, Williams said.
San Francisco fire Lt. Ken Smith said three people were hurt in the blast. Two suffered second-degree burns and the third suffered head and neck pain. A fourth victim was taken to the hospital for an unrelated medical condition.
A 2-year-old child at a home next door was treated at the scene after being hit in the face with glass, according to Smith.
When firefighters arrived at the home, they found a small fire still burning and were able to quickly extinguish it, Smith said. The front of the house had been blown out.
Williams said two homes next door and three homes across the street remained evacuated this morning.
The American Red Cross was called to the scene to assist residents who were displaced.
Authorities remained at the scene overnight to monitor the home and are waiting until the structure has been deemed secure to make entrance today, Williams said.