Undated (AP) _ A gas explosion and fire demolished a lake resort home near Grove, Okla., on Tuesday, killing an 8-year-old girl, her grandfather and great- grandmother, while in Illinois, a smoldering cigarette set fire to a boarding house, killing three and injuring six others.

The Oklahoma blaze also seriously injured the girl's 60-year-old grandmother.

The girl, Amie Davis of Joplin, Mo., was spending the night with her grandparents, John and Kathleen Snider, and her great-grandmother, Maggie Opal Jacobs, 85, when the blast occurred at 2:27 a.m.

Mrs. Snider was admitted to Hillcrest Medical Center in Tulsa with second- and third-degree burns to her legs, hospital officials said.

The owners of the house near Elk River, about five miles northeast of Grove, were converting from propane fuel to natural gas and had planned to have the work completed Tuesday, said Fire Chief David Fischer.

''The walls blew out, the roof came down and the house had virtually burned up by the time we got there,'' Fischer said.

The bodies of the girl, her 62-year-old grandfather and great-grandmother were found in the rubble, Fischer said. The girl's parents were spending the night in a nearby mobile home.

More than 20 people were left homeless in the fatal pre-dawn fire at the three-story Rosedale Home in Jacksonville, Ill.

Two of the victims died of burns and smoke inhalation after they became trapped in the first-floor lounge where the fire started, said Morgan County Coroner Jeff Lair. A third person died of smoke inhalation in her bedroom, he said.

The cause of the fire was listed as undetermined, but Jacksonville Fire Capt. Harry Cook said it was believed to have been started by a burning cigarette in a padded recliner chair.

The dead were identified as Clarence Scott, 84; Marilyn Adams, 49; and Dora Houser, 76.

Another resident of the home, Agnes Milburn, 75, was transferred to the burn center at Memorial Medical Center in Springfield, said Sue Cathcart, a hospital spokeswoman. She was listed in critical condition with second- and third-degree burns over 30 percent of her body.

Five other residents were admitted to Passavant Hospital in Jacksonville, suffering smoke inhalation and minor burns. All were in good condition, said nursing supervisor Patty Crawford.

The homeless were being assisted by the Salvation Army.