Explosion rips 1st floor of S.F. house SAN FRANCISCO Sudden boom leaves 5 people hurt, garage ruined in Sunnyside

An explosion badly damaged a house at 108 Congo Street in San Francisco. Five people were injured in the blast. An explosion badly damaged a house at 108 Congo Street in San Francisco. Five people were injured in the blast. Photo: Photo Courtesy Of Hugh D. Byrne Photo: Photo Courtesy Of Hugh D. Byrne Image 1 of / 7 Caption Close Explosion rips 1st floor of S.F. house 1 / 7 Back to Gallery

With a sharp booming sound that sent dozens of people scurrying into the street, much of the first floor of a house in the Sunnyside neighborhood of San Francisco exploded Monday night, shattering the home's garage and injuring five people.

Luke Konigsmark said he was in the home with several friends and relatives when suddenly, around 7:45 p.m., the whole house shook with what sounded like a bomb going off on the bottom floor.

"That was the craziest thing that ever happened," Konigsmark, 19, said as he stood, dazed, outside the wreckage of his house. "I'm in shock. I just about had a heart attack."

The two-story, wood-frame house at 108 Congo St. rocked with the impact, and then everyone who could move bolted onto the sidewalk, authorities said. There, they found that the garage had been turned into a blackened hole littered with splintered timbers, with a small fire blazing in the rubble.

Konigsmark, clutching his 20-year-old cat Paws in his arms, huddled with relatives in shock as neighbors - who had also run outside - comforted them.

Firefighters quickly arrived and extinguished the flames. Two men suffered second-degree burns that were not life-threatening, and they were taken to St. Francis Memorial Hospital, authorities said. Two others, including an elderly woman, were also taken to a hospital. A 2-year-old child who was next door was injured by flying glass and treated at the scene.

"We don't know what it was, but it was a pretty big boom," said San Francisco police Officer Brian Oliver. "We had a lot of calls."

Five houses near the damaged home were evacuated, and authorities roped off the area for the night. Not knowing if there might be a follow-up explosion, investigators said they would wait until morning light before they went in to inspect the scene.

"We don't know the cause," said police Lt. Neville Gittens. "We can't get in to figure it out because it's too dangerous."

A source close to the investigation said all possibilities were being examined, from a gas line leak to a bombing.

Konigsmark said he thought the explosion might have been caused by a gas leak because "it happened on the side where the gas line is in the basement." He said his 27-year-old brother, David Konigsmark, was among those injured, and that David was downstairs in a room next to the explosion when it occurred.

Also in the house was David Konigsmark's son Luciano, 7, and David and Luke's brother, 16-year-old Noah Riccardi.

The brothers' father, John Konigsmark, said five of his children and one grandson live in the house.

Neighbors along the tree-lined street of tidy bungalows and cottages described the residents of the exploded house as "nice," but in the shock of the incident did not want to be quoted.

"We don't know what goes on behind closed doors," said one neighbor. "It's personal and tragic. I feel really bad for them."