One person was killed and another injured early Monday in a three-alarm house fire in Crafton, authorities said.

Firefighters were dispatched at 5:15 a.m. to a three-story, brick house on Elmwood Street, where two people were reported to be trapped inside, Crafton fire Chief Mike Crown said.

“The house fire was pretty well off,” Crown said. “And we went to work.”

Officials did not identify the person killed in the fire. That typically is done by the Allegheny County Medical Examiner’s Office.

Firefighters pulled another person from the burning house, Crown said. They were taken to a hospital, but the extent of their injuries was unknown.

A third person managed to escape the fire on their own, Crown said.

Heavy smoke was reported nearly an hour after firefighters were dispatched, according to an email alert system. Firefighters had the blaze under control by 8:23 a.m.

The fire gutted but did not completely destroy the house, Crown said. Various parts of the floors and ceilings had collapsed.

As firefighters battled the fire, one hydrant appeared to be frozen but, after a few minutes, waterflow was normal, Crown said.

The temperature dropped to about 10 degrees, with a wind chill of -3, around 6 a.m. at Allegheny County Airport, according to the National Weather Service.

The Allegheny County Fire Marshal is investigating the cause and origin of the fire.

Allegheny County Police sent a homicide unit to the scene, Lt. Venerando Costa said. That regularly occurs during when fires produce fatalities and doesn’t indicate suspicion, he said.