Eight people including three children were injured in Philadelphia on Monday when a natural gas explosion tore through a row house under renovation, causing the collapse of three houses and the evacuation of about 70 homes.
Among those injured was a man who was hospitalized with severe burns and listed in critical condition and a child who had suffered minor injuries, the office of Philadelphia Michael Nutter said in a statement.
Firefighters were searching the rubble with listening devices to ensure that no one remained trapped, the mayor's office said.
Residents reported a strong smell of natural gas after the blast and Philadelphia Gas Works crews shut off gas to the area, utility spokeswoman Melanie McCottry said.
Hundreds of people watched as emergency workers and firefighters went about clearing 15 feet of rubble and debris that spilled onto the street from the collapsed home.
One resident of the neighborhood, Diane Schaffer, said the smell of gas had permeated the area since early Monday morning. After the explosion, she put her son and a neighbor's daughter in her car and fled the area.
"I could hear a guy saying, 'Help me, help me,' but when I looked back, I saw two guys running towards him, so I felt OK about leaving," Schaffer said. "We just sped off."
Early last month, a four-story building under demolition in the city collapsed, killing six people and injuring 14 as it fell onto an adjoining Salvation Army Thrift Store, burying shoppers in debris.