The body was not discovered until late in the day, some distance from the home, after authorities had thought the neighborhood had escaped the blast without any deaths. Police were working to establish the victim's identity, Lt. Ron Lunetta said, adding that no one else was believed to be missing.
At least 55 units in the complex were damaged, police said, including the house that was leveled, and seven others that were "pretty much destroyed," Fire Marshal Bill Erney said.
The events leading to the explosion began with a contractor working to replace electric service to the house that later blew up, officials from the utility PSE&G said. Around noon, the utility got a call that the contractor had damaged a gas line.
Crews were repairing the line about an hour later when, PSE&G spokeswoman Lindsey Puliti said, "there was an ignition."
The force from the explosion buckled windows in an apartment complex nearby, said resident Marsha Brown, and pictures fell from her walls.
"It felt like a bomb," she said.
She ran to the town house complex, saw a home engulfed in flames and two utility workers on the lawn with injuries that apparently included broken bones. She said she saw another worker on a sidewalk crying, being held by a woman.
At least one home was a blackened pile of rubble, and others had damage, including windows that were blown out. Debris was widely scattered, with insulation hanging in some tree branches.
"My body was shaking. I like to say I am calm, but I was shaking," said Brown, who had a day off from her job as an infant hearing screener at a hospital. "You could feel the flames, everything."
A resident of the complex, Bryan Gentry, drove home minutes after he heard an explosion and as he got closer, saw a black smoke cloud. The fire was intensely hot, he said, and he saw one person walking away from the fire who appeared to be stunned.
"It was just unreal," he said, adding that emergency crews responded "really fast."
The seven people injured were all utility workers, authorities said. Just three of those victims, all close to the blast, had to be hospitalized and none of those injuries was considered life-threatening, said Dr. Louis D'Amelio, trauma chief at Capital Regional Medical Center in Trenton. They included concussions, broken bones and minor shrapnel wounds, he said.
Normally during that time of day, most people in the neighborhood are at work and their kids are at school, Gentry said.
Though the damage to the pipeline caused a gas leak that could lead to an explosion, the pipeline itself did not explode, a spokesman for the utility said.
Mulvihill reported from Trenton. Associated Press writer Kevin Begos in Pittsburgh also contributed to this report.