Nearly 24 hours after a building under demolition collapsed on shoppers and staff at a neighboring thrift store, killing six people and injuring 14 others, rescue crews searched through the rubble for survivors.
About 75 percent of the site in downtown Philadelphia had been scoured by early Thursday morning as part of an around-the-clock search for life amid the mountain of crumbled concrete and splintered wood, Mayor Michael Nutter said at a news conference on Thursday.
Late on Wednesday, 12 hours after the 10:45 a.m. EDT (1445 GMT) collapse, a 61-year-old woman was pulled from the debris and rushed to the hospital in critical condition. Earlier in the day, six people were found dead and 13 others were rescued with minor injuries.
At the news conference on Thursday, Fire Commissioner Lloyd Ayers said his team "stayed the course" and would do so until the entire site was searched.
"All of the despair with the people who were deceased, that person being pulled out alive is what every rescue is all about," Ayers said.
Investigators were trying to determine what caused the four-story building that was being demolished to collapse onto a neighboring Salvation Army Thrift Store, burying shoppers in the debris. On the scene investigating were Philadelphia police, Philadelphia Licenses and Inspection and the Occupational Safety and Health Administration.
The mayor suggested at a late-night news conference on Wednesday that the number of casualties could rise.
"We still do not know how many people were inside the thrift store or possibly on the sidewalk" at the time of the collapse, Nutter said. "If someone else is in that building, they will find them."
Authorities declined to identify the dead other than to say that they included one man and five women who had all been inside the store when the building next door came down.
Most of the injured were also thought to have been inside the store or on the sidewalk in front of it at the time. Aside from the last woman rescued, most were said to be in stable condition or have already been released from the hospital.
Witnesses to the sudden collapse, which occurred at 22nd and Market streets in the heart of Philadelphia's busy Center City district, said it shook the ground and knocked people on the nearby sidewalk off their feet.
One witness, Dan Gillis, 31, a construction worker from New Jersey who was on a job across the street, said he saw a crane remove a supporting beam from the front of the building and then the wall next to the thrift store began to sway.
Jeffrey Fehnel, 48, of Philadelphia, said a backhoe hit the rear side of the building at about the same time. "The building came down. It was like a big blast," he told Reuters.
Authorities said the building that was being demolished had housed an X-rated book and video store.