Mark Keeley, the 19-year-old utility worker killed in the Tacony natural-gas explosion, was a "throwback kid," a former assistant principal recalled of the 2009 graduate of Cardinal Dougherty High School.

"He respected his elders. He respected authority," said Mary McDonald, now an assistant principal at Archbishop Wood in Bucks County. "He had a great sense of humor, but he knew where to draw the line."

His family, McDonald said, instilled those values in him.

There were plenty of tears Thursday evening at a prayer service for Keeley inside the parish auditorium at St. Cecilia's Church in Northeast Philadelphia.

But there were happy, sometimes funny, recollections of a cheerful young man.

Joe Mazza, his brother-in-law, drew laughter from among the several hundred people in attendance when he said Keeley would probably want to tell everyone there, "Yeah, it sucks that I'm dead, but don't be upset."

Rick Leonetti, a former teacher and coach at Cardinal Dougherty, recalled how he met Keeley outside class, and they would talk baseball. Leonetti went to see Keeley play, and they became friends.

"He was Cardinal Dougherty. He loved the school," Leonetti said. "He was just a great kid."

Cardinal Dougherty closed last year after the Class of 2010 graduated.

Keeley's family, including his mother, Peggy, father Tom, sister Lauren, and brother Tom, were consoled by friends and other well-wishers after the prayer service.

They declined to speak with the media.

The Rev. Carl Janicki said a life-celebration vigil for Keeley would be held at the church at 7 p.m. Thursday and again on Saturday at 9 a.m., with the liturgy to follow at 11:30 a.m.

Keeley was a rookie employee at the Philadelphia Gas Works when he and other workers and city firefighters responded Tuesday night to a natural-gas leak at Torresdale Avenue and Disston Street. Then a pipeline exploded.

Keeley's body was found in the debris of a chiropractor's office destroyed by the blast and ensuing fire.

A firefighter and five other PGW workers were injured. Three PGW workers remained in the burn unit Thursday at Temple University Hospital.

The cause of the explosion is under investigation.

Contact staff writer Robert Moran at 215-854-5983 or bmoran@phillynews.com.