An apparent natural gas explosion about 10:45 p.m. EST Wednesday killed five people, including a four-month-old child, in Allentown, PA, police said. A fire following the explosion affected a total of 47 properties, including 10 businesses, and forced more than 750 people to evacuate over a three-block area.

Response to the fire was hampered by packed layers of snow and ice that prevented emergency responders from repairing a ruptured underground natural gas line that was feeding the fire, said Allentown Fire Chief Robert Scheirer. The blaze was extinguished early Thursday.

Two houses were destroyed and six houses that caught fire after the explosion are a complete loss, Scheirer said. No known gas odor preceded the blast, he said during a news briefing.

Allentown Police Chief Roger MacLean said the epicenter of the explosion was at the home of Beatrice Hall, 74, and her husband, William, 79, who were killed. A four-month-old boy, a 16-year-old girl and a 69-year-old woman also were killed on the block where the explosion occurred.

An investigation has begun, Scheirer said.

Early Thursday UGI Corp. spokesman Joseph Swope said the company was "going under the assumption that it is a gas explosion, but that has not been confirmed to be the case." He later told reporters that the incident "has the look and feel of a natural gas explosion."

The 12-inch diameter low pressure gas main apparently involved in the explosion had no leak history and a routine check for leaks was conducted Tuesday in the area with no findings, UGI stated. Subsidiary UGI Utilities Inc. provides gas and electric services to Pennsylvania and Maryland customers. PPL Electric Utilities, which serves the area, said about 150 residents were without power after the fire downed dozens of power lines.

David Van Allen, who manages Allentown's emergency medical services, said 19 paramedics were on the scene along with five of the 10 mutual aid companies that originally responded. Eight people, including one firefighter, were taken to hospitals with minor injuries, either from the explosion or from being evacuated, he said.

"This is a real tragedy," Allentown Mayor Ed Pawlowski said in a statement from Florida. He was planning to return to Allentown on Thursday. "We have a gas explosion. Right now they're trying to close off the gas lines. We've evacuated folks for safety purposes. Our emergency plans we worked on for disasters are in place, they're working...

"Our thoughts and prayers are with the families. I'm getting updates from the fire chief, our emergency management team, director of our health bureau as well as our police chief...From what I understand things are running smoothly in this difficult time. We are definitely concerned about the families who have been affected by this fire...

"This is a dangerous time of year with freezing, expansion and contraction of the lines because it gets cold," the mayor said.

A press conference was held Thursday at Allentown's Gross Towers seniors apartment complex, which was evacuated following the explosion. Ironically, a gas leak at the complex in 1994 triggered two explosions and a fire, killing one person and injuring more than 60 people.

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