Over 400 people gathered at St. Cecelia Catholic Elementary to hug and console one another and pay respects to Mark's father, his mother and other family members for their loss and to offer prayer.
Those who knew Mark at his former high school, the now closed Cardinal Dougherty, spoke fondly of the 19-year-old.
"Just very positive, he was a person who walked into a room and lifted the people that were in the room," Father Carl Janick, former school president, said.
From the student to teacher, their feelings about Mark are the same.
"He made everybody laugh no matter what it took, he's going to be very much missed," former classmate Kim Kashnoski said.
"He was always laughing, he always made everyone feel better, he loved Cardinal Dougherty, he loved baseball, he loved the Phillies, he was just a great kid," Mark's former teacher Rick Leonetti said.
Keeley's brother-in-law Joe Mazza spoke on behalf of the family thanking everyone for their support.
"If you knew Mark, he'd probably be saying, 'yeah, it sucks that I'm dead, but don't be upset, be happy,' and like one of Mark's tattoos said, 'live every day like it's your last," Mazza said.
Keeley was killed and 4 other PGW workers and 2 firefighters were injured as they were trying to shut off a 12-inch high pressure gas main that ruptured on the corner of Torresdale Avenue and Disston Street in Tacony Tuesday night.
Earlier in the day Thursday, Keeley's family gathered at the site of the explosion.
It was a quiet moment of silence as family and friends of Mark solemnly made their way to the blast site.
Mark's father, Tom, a longtime PGW worker himself, was comforted by colleagues. After surveying the devastation, they prayed and remembered a young man lost too soon.
The explosion has left a lasting impact on the tight-knit Tacony neighborhood. Many residents stood by and watched as the family arrived.
The moment was an emotional one for John Finchem.
"Very sad," Finchem said, going on to say that even though he didn't know Keeley, this was hitting him pretty hard. "He was just a young kid."
Others, like Jack Coyle, arrived to see what was left. Coyle's wife owns the hair salon "Vanity Villa." The city said her shop will have to be razed, but, while she'll have to start over, the Coyles' thoughts were instead with the Keeleys.
"Our main concern was the family of the boy, the young man that lost his life. That was more important than anything. Ours is just stuff," Coyle said.
Investigators have not yet ruled on an official cause of the explosion. However, on Thursday night, Action News learned that investigators are looking into a repair that had been made on the pipe some 200 feet from the explosion last month. The pipe, made of cast iron is 71 years old and is part of an aging infrastructure that PGW spends $50 million annually to replace with steel or plastic.
Meanwhile, at the vigil, Keeley's family also sent their thoughts and prayers to the others who were injured in the explosion.
A life celebration vigil for Mark Keeley is set for Thursday night at 7:00 p.m. at St. Cecelia's Catholic Church to be followed by a Mass of Christian Burial at 11:30 Saturday morning.