That worker was originally reported as missing but, just after 11:00 p.m., authorities told Action News that the worker's body was found under debris.
He has been identified as 19-year-old Mark Keeley. He was a distribution worker who had been working for PGW for just over a year.
The memo goes on to quote company president Thomas E. Knudsen as saying "I would like to extend our sincerest condolences to the Keeley family, Mark's friends and coworkers; and also our continuing support to the family, friends and coworkers of those in hospital."
Keeley was a 2009 graduate of Cardinal Dougherty High School. He was a member of the baseball team.
"The one thing about Mark, Mark was a heck of an athlete, could run like a deer, and I always used to kid him. As fast as he was on his feet, he was with his wit. He was a funny kid," Mark's high school coach Steve Carr told Action News.
PGW officials say he'd been on the job about a year and his father, Thomas, has been a longtime pipe mechanic of the company.
His family has requested privacy as they mourn the loss.
Two firefighters were also injured in the blast. They were treated and released for minor facial debris injuries suffered at the scene.
On Wednesday, investigators said they were still looking into the cause. They said there was no history of maintenance problems in the area.
The explosion followed a 12-inch high pressure gas main break in the 6900 block of Torresdale Avenue around 7:20 p.m. Tuesday.
Officials say while working the break something went wrong and the main ruptured around 8:30 p.m., causing an explosion.
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A second alarm came in at 8:35 p.m. and just before 9:00 p.m., a third alarm was struck. Two buildings caught fire as a result of the explosion.
Resident Jim McNichol said, based on a warning from his landlord, he left his second-floor apartment just seconds before the blast.
"I held by breath and grabbed what I had to get, came out, then 15-20 minutes later, I was down the street here... Bang!" said McNichol. "It was like a war zone."
Another witness couldn't believe what he saw.
"While they were digging to get to the main, it blew up right there. I was 50 feet from it, it was unbelievable," witness Chris Labovitz said. "The fireball was 30, 40 feet high."
The fire was placed under control by 11:00 p.m.
At least 30 people were evacuated while crews worked on the break prior to the explosion. Some were sent to the Disston Recreation Center at Glenloch and Disston streets.
By Wednesday, some residents were being allowed back into their homes. The exceptions were the people who live in rowhouses right next to the blast scene.
The Associated Press contributed to this report