By Anita Oh

HAMBURG, Pa. (CBS) — It’s been a tragic Labor Day weekend for one family in Hamburg after a massive overnight fire as officials say a pregnant woman and her two children were killed.

“It was absolutely just an inferno,” said neighbor Nick Richardson. “When I came on the corner, I just couldn’t believe the intensity of the fire and how big it was.”

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Richardson took a video of the massive flames erupting from this home on the 400 block of South Fourth Street in Hamburg around 11:30 Saturday night.

“It was just a wall of flames – everything was just a very hot ball of flames,” he said. “It was impossible for anyone to even get in there.”

Up to 70 firefighters battled the blaze, which moved quickly through the two-and-a-half story home.

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A woman and her two kids, ages five and two, did not make it out, authorities say – but a man inside jumped to safety from a second-floor window and is being treated for minor injuries.

Police say the woman was pregnant with her third child.

The children’s father was able to jump from the second floor bedroom window to safety. Officials say he was taken to the hospital and treated for minor injuries.

At this time, authorities are not releasing the names of the victims – but those who knew the family, even in passing, are grappling with the loss.

“I was devastated at that point,” he said. “It was really tragic, very horrible. My heart goes out to the family. This is tragic.”

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Pennsylvania State Police are now investigating. No word on a cause at this time or whether this fire was suspicious.