Beck said he called 911, ran over, and climbed the fence, then realized the couple were still inside the collapsed building.
"I was just like, 'Oh, my God.' I knew they were home. I could see their cars, I knew they were in there," Beck said.
A group of neighbors went to work immediately, even as smoke began to rise from the burning building, Beck said.
"There had to be a dozen or so neighbors trying to pull debris off. A couple of the men went to the front, some of them went to the back," Beck, 63, said by phone Thursday evening. "They brought the wife out first, husband right behind . . . within two, three minutes of the explosion they were out of there."
"By then it was really burning pretty good - the front doors were blown down the street," Beck said. "It was a really horrific blast."
Police, fire, and medical personnel arrived moments later, Beck said, and the immediate area was evacuated for about an hour and a half.
"The cavalry came very quickly," he said.
The investigation continued Thursday evening, Beck said.
About 7 p.m., he said, there were "a hundred people over there . . . combing the area. Got everybody over there."
What caused the explosion was unclear in the immediate aftermath. While speculation among residents noted the recent installation of new gas lines on the street, Michael Voll, the township manager, said he had been told that preliminary indications were that they had not caused the blast.
The police chief, Voll said, had told him there was a propane tank on the property, but no definitive cause would be available until after an investigation. The federal Bureau of Alcohol, Tobacco, Firearms and Explosives will begin an investigation Friday, Voll said.
Beck, a retired lieutenant in the Philadelphia Police Department, said he hoped people would pray for the couple.
"Our hearts go out to them, and I'm grateful especially to the heroes that went over there and risked their lives to try and save theirs," Beck said.
"They're a good couple. I hope people keep them in their prayers and they can recover. You can put the house back together, but it's going to be a road for them to get back to where they were."