Mark Keeley was only 19, fresh out of Cardinal Dougherty High School when he joined his father last year as a full-time PGW employee.
At the accident site, PGW and local, state, and federal investigators have begun to search for answers to what caused the explosion.
It's a problem experts said they have seen many times before.
"This type of explosion isn't that unique. It happens every four or five days," said Carl Weimer, head of the Pipeline Safety Trust, an advocacy group in Washington state.
Finding answers could take months - or longer. Federal investigators are still searching for the cause of a September gas explosion in California that killed eight people and destroyed dozens of homes.
At Torresdale Avenue and Disston Street on Wednesday afternoon, about 200 people gathered to gaze at the wreckage.
Geraldine Dixon, 48 - a care worker at the Disston Manor Personal Care Home, about a block from the Disston Chiropractic & Rehab Center, where the explosion occurred - said firefighters came to the nursing home Tuesday night and told residents the building was being evacuated. Dixon said she and others quickly walked about 22 residents to the Disston Recreation Center two blocks away.
"No sooner than I got them inside the building, the first explosion went off," Dixon said. "I came running out, and there were flames everywhere."
She said papers from the chiropractor's office were raining down up to three blocks away.
"It was like it was snowing," Dixon said, adding that the entire second floor of the chiropractic office was blown onto the roadway on Disston.
By midday Wednesday, residents in all but three homes had been allowed back to their houses. About 40 people had been forced out.
At Marsden and Disston Streets, Brian Nugent, 29, said he was inside his home when he heard the explosion.
"The whole house just shook. I hit the floor because I thought there might be another explosion," Nugent said. He went outside and saw firefighters running down the street, shouting, "Get out of the house! Run!"
The blast shattered the windows of the two-story building that was home to Georgeanne Huff-Labovits' beauty salon, Marie Huff Hairdresser. It sits across Disston Street from the chiropractic center. Her mother opened the salon 30 years ago, but she has been in charge for the last two decades.
"I haven't been in my building. I don't know what it looks like," Huff-Labovits said. "We're getting conflicting reports that they're going to tear it down."
She was relieved to learn that the two tenants of her apartments had been evacuated before the explosion.
"That's what I care about," she said.
She was lucky compared with the Keeley family, she said. Keeley's body was found amid the debris of the chiropractor's office.
"You can't bring back a life," said Huff-Labovits. "My prayers go out to the person who died."
Keeley came from a close-knit family. He loved sports and was especially a fan of Cliff Lee, Steve Nash, and Pistol Pete Maravich.
His last post on Facebook, at 11:32 a.m. Tuesday, read, "I Wish PGW Shut Down For The Rain."
His sister, Lauren, is a teacher and an Eagles cheerleader. A woman who answered the phone at the family home said relatives did not want to talk and requested privacy.
Two PGW workers and a firefighter were released from Aria-Torresdale Hospital on Wednesday. Three others who were injured remained in the burn unit at Temple University Hospital.
In a statement, PGW chief executive Thomas E. Knudsen expressed sympathy.
"On behalf of PGW's officers and the entire PGW family, we extend our sincerest condolences and our continuing support to those involved in this tragic incident," the statement said.
The last time the company had an explosion that involved the loss of life was in May 1979, when seven people died in a blast in Bridesburg that leveled a neighborhood bar and a rowhouse. The explosion at Tacony and Margaret Streets was described at the time as the worst tragedy in the history of the Philadelphia Gas Works.
Among those who died in that blast were Edward J. Brown Jr., who was the first PGW employee ever to be killed on the job; five men in the bar; and a man who was struck by debris while waiting for a bus. Nineteen people were injured.
PGW spokesman Douglas Oliver said the Philadelphia Fire Department would lead the investigation into Tuesday's explosion.
Executive Fire Chief Daniel Williams said gas workers were using cameras at the scene to check other sections of the main to ensure the explosion didn't create additional cracks.
The Pennsylvania Public Utility Commission also had investigators at the explosion site. The Pipeline and Hazardous Materials Safety Administration, part of the U.S. Department of Transportation, is involved in the probe as well.
In 2009, 80 similar accidents killed nine people and injured 50, according to the Transportation Department.
Digging by a contractor can nick gas lines, leading to explosions. Frequent freezing and thawing also causes cracks, especially in pipes that are cast iron, as most of PGW's are, Oliver said.
He said that he did not know Wednesday whether the gas main that exploded in Tacony was cast iron, but that the call Tuesday night complaining of gas was the utility's first report of a problem there.
Mark McDonald, president of the New England Gas Workers Association, which is not a union but advocates for industry workers, said companies were supposed to patrol for leaks during the winter. A spokeswoman for the PUC said its records showed that PGW had done so.
Contact staff writer Miriam Hill
at 215-854-5520 or firstname.lastname@example.org.
Inquirer staff writers Melissa Dribben, Jan Hefler, and Robert Moran contributed to this article.