A 14th survivor was pulled from the rubble of a collapsed four-story building in central Philadelphia minutes after officials said six people were killed and at least 13 people were injured.
Rescue workers used buckets and their bare hands to move bricks and rubble to free a 61-year-old woman late Wednesday night identified as Myra Plekam of Kensington, Pa., Philadelphia Public Safety Director Michael Resnick said.
Plekam was taken to the Hospital of the University of Pennsylvania and listed in critical condition.
Plekam's rescue came more than 12 hours after the mixed-used building collapsed. Resnick said Plekam was the last person officials knew of trapped in the rubble. Officials caution, however, that there could still be people trapped that the fire department didn't know about.
WATCH: Woman Pulled From Philadelphia Building Collapse
Minutes before the woman was pulled from the rubble, Philadelphia Mayor Michael Nutter said one man and five women were among the dead, but did not release their names at a late-night news conference.
At least 13 other people have been transported to hospitals with minor injuries, according to authorities.
"This has been a tough day here in the city of Philadelphia but we're a pretty tough city and we're quite resilient," Nutter said.
Fire officials said that 40 percent of the collapsed building still needs to be checked. Officials declined to say how much longer they will remain at the site to search for potential survivors, but Nutter insisted that the search will continue through the night.
"We did not know and we still do not know how many people were actually in the store or possibly on the sidewalk or some other area adjacent to the Salvation Army thrift store," he said.
The vacant building was in the process of being demolished when an exterior wall that it shared with an adjoining building fell outward Wednesday morning, collapsing into the adjoining two-story building that housed a Salvation Army Thrift Store, where most of the injuries occurred. The thrift store was damaged but is still standing.
Officials at the University of Pennsylvania hospital, which treated five victims, said that they saw mostly cuts and bruises on victims. At least one victim has already been released, and others were expected to be discharged sometime Wednesday.
"They were a bit stunned, they were saying they heard a loud noise and then the ceiling began falling," Dr. Elizabeth Datner said at a news conference Wednesday. "We saw one individual who had been trapped, but they are all talking and all in stable conditions."
Datner said most of the victims were in the thrift store at the time of the collapse.
The vacant mixed-use commercial building was in the process of being demolished when it collapsed, according to city inspector Carlton Williams. Authorities are unsure how many construction workers were at the site when the building collapsed.
Firefighters were first dispatched to the building at 10:43 a.m. and arrived at 10:45 a.m. to begin working, Fire commissioner Lloyd Ayers said.
Eyewitness Dan Gillis was just working across the street when the building collapsed.