Three people including a 4-month-old child were dead and two were missing Thursday after a massive natural gas explosion demolished two row homes and set six others ablaze in eastern Pennsylvania.

Allentown fire Chief Robert Scheirer said a two-story row house exploded about 10:45 p.m. Wednesday. An elderly couple who lived in the home died. They were identified by their daughter-in-law as Beatrice Hall, 74, and her husband, William, 79, the Allentown Morning Call newspaper reported on its website.

The baby was not identified.

UGI Corp. said Thursday morning that one of its natural-gas pipelines likely exploded.

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The fire that burned for hours was put out after gas lines were shut down, and 500 to 600 residents who were evacuated were allowed to return to their homes.

Allentown fire Chief Robert Scheirer said early Thursday that the fire consumed an entire row of homes.

Images from NBC station WCAU showed flames reaching hundreds of the feet into the air from the scene of the blast. The explosion was so powerful it was felt nine miles away in Bethlehem, Pa.

The blaze was put out early Thursday, delayed by the difficulty of digging through packed layers of snow and ice to a ruptured underground gas line that was feeding the flames, Scheirer said.

Residents were allowed to return home early Thursday. They had been taken to a Jewish community center and an agricultural hall at the city's fairgrounds while emergency crews worked overnight.

The blast also downed dozens of high-power electrical lines, according to radio reports monitored by the Morning Call and PPL Electric Utilities shut down power in the area.

'Under attack'

The blast was so powerful that it sent a flat-screen computer monitor sailing into the back of Antonio Arroyo, whose house was on the opposite end of the row from the house that exploded.

"I thought we were under attack," he recalled from a shelter where some 250 people took refuge in the hours after the blast.

Arroyo and his wife, Jill, both 43, lost their home in the fire.

Antonio said he ran outside and saw that an entire house had been leveled, a fireball now raging in the spot where it once stood.

"What I saw, I couldn't believe," said Arroyo, a community volunteer.

He and his wife, a nurse, fled their home with only the clothes on their back. They planned to return at daylight to see what they could salvage. Jill Arroyo broke down sobbing when she recalled her son's athletic memorabilia - likely lost in the blaze - including DVDs of his high school football games.

"The DVDs are gone. All his trophies are gone. All gone," she sobbed as her husband comforted her.

'It's gone'

Another onlooker near the scene of the fire, Leonard Hein, said the blast sounded like a military rocket.

"I thought I was back in Vietnam," he told the Morning Call.

Dale Dalrymple told the Lehigh Valley Express-Times that he lives directly across the street from the destroyed home.

"I was in the basement watching a movie with my granddaughter," Dalrymple said. "All I felt was like a suction and a big boom and I ran upstairs and here my front door was blown open."

After fleeing his house in temperatures below freezing he said he saw flames coming from the second story of the row home that had been attached to the destroyed home.

"The house is not even there. It's gone," he told the Express-Times.

Tricia Aleski, who lives a few blocks away, said the explosion jangled her nerves.

"I was reading a book in the living room and it felt like a giant kicked the house. It all shook. Everything shook," she said. "I checked the stove and everything, (to) make sure everything's off."

Jason Soke was watching college basketball when he heard and felt the explosion. It rattled his windows. He went to the third floor and looked out and saw flames and smoke.

"Your senses kind of get stunned," he said. "It puts you on edge."