Lehigh County Coroner Scott Grim identified the deceased as 79-year-old William Hall, 69-year-old Ofelia Ben, 16-year-old Katherine Cruz and Cruz's 4-month-old son Matthew Vega.
DNA tests are being conducted on the body of a fifth victim, a woman discovered in the rubble. The Morning Call newspaper identified her as William Hall's wife, Beatrice, citing the couple's daughter-in-law.
The fire raged for hours while utility crews worked to turn off the supply of natural gas that was feeding the flames. The blast late Wednesday flattened two homes and damaged more than 40 buildings.
Investigators and utility workers picked through the smoldering ruins, trying to determine whether an 83-year-old cast-iron gas main was the culprit.
Meanwhile, victims of the blast and resulting fire spent Friday trying to figure out what to do next. One of the victims, Rebecca Potts, returned to the scene to watch heavy equipment operators demolish what was left of her damaged house.
"We were moving things in and waiting to build a life together," Potts said. "Not now."
Some residents who live across from the blast site say looking at the debris makes them sad and angry for the loss of life and property and scared about the idea of moving back in.
"I'm scared to even turn on my stove now. I can't trust UGI telling me 'Oh, yeah, your gas line's alright.' That's what they said two days ago before the blast," said Jose Arzuaga. "Guys come out here did an inspection, said everything was ok, now I got five of my neighbors that passed away."
UGI crews were on the scene on Friday trying to inspect a 12 inch gas line with a camera to check for cracks.
"We don't know anything about the cause at this point actually until we get that pipeline checked out," said Allentown Fire Chief Robert Scheirer.
A close up look at the neighborhood testifies to the power of the explosion, which blew out the doors at a nearby carwash and broke windows at numerous properties.
What no one can fix is the loss and uneasiness this neighborhood is feeling after Wednesday's fatal blast and fire.
The Associated Press contributed to this report.
