Fire engulfed a house here early Wednesday,killing four children and their mother, authorities said. The woman's husband was critically burned.

The fire in the 11/2-story frame house in this Indianapolis suburb broke out about 3 a.m. State police believe a new gas furnace was installed in the home recently and might have caused the fire, Trooper Shelli Jones said.Resident Roy Westcott, 34, was reported to have installed the furnace himself last weekend.

A next-door neighbor, Hal Ford, 51, said the blaze broke out soon after he returned home from work.

Ford said he heard an explosion and saw through a large picture window in the Westcott home that one of the rooms was engulfed in flames.

However, Sugar Creek Township Fire Chief Jerry Nulliner said there was no evidence of an explosion.

Ford said he and his family rushed to the Westcott home.

"We got a window open, but we couldn't get in," Ford said. "There was black smoke just pouring out of it. We knew it was too late at that time."

The family said Westcott was running around outside the house, yelling, "Get the gas turned off, get the gas turned off!"

Killed were Westcott's wife, Julia M. Kennedy Westcott, 34, and her daughters Brandi Kay Neal, 16, Holli Ann Neal, 14, and Veronica Marie "Vonnie" Westcott, 6, said Hancock County Sheriff Nick Gulling.

The couple's son, Joshua Andrew Westcott, 4, was pronounced dead at a hospital, authorities said.

Mrs. Westcott and the children were found in the home's three bedrooms. Two were found in their beds, two on the floor and one in a closet, Gulling said.

Westcott was flown to Methodist Hospital in Indianapolis, where officials said he was listed in critical condition with burns over 27 percent of his body.