MOULTONBOROUGH, N.H. (AP) – A young child was killed and six other members of her extended family injured when a series of explosions turned a lakeside home into “an incredible inferno” and a pile of rubble.

The victims were three generations of the same family, apparently staying at the home for the long holiday weekend, said police Chief Scott Kinmond. He said five of the six were treated and released for mostly cuts and bruises. A sixth still was hospitalized Sunday.

The fire marshal’s office reported Sunday that propane gas ignited, causing the explosion and fire. Officials still were trying to determine the source of the ignition and the sequence of explosions at the home on Ash Cove on Lake Winnipesaukee.

Fire marshal’s investigator William Clark said the home’s propane tank ruptured, and investigators were working to find out if the tank was involved in the initial blast, or was damaged and exploded afterward.

Kinmond said the child’s body was found around 5:20 a.m. Sunday, after searchers called in heavy equipment to help remove rubble. No names had been released as of Sunday morning.

Paul Sampson, a neighbor, said he and a group of family members and neighbors were outside around 9:40 p.m. when the house across the water roared into flames.

“It was an unbelievable explosion. It was terrible,” he said. “The house was an incredible inferno.”

Sampson said his son Dennis, his neighbor Jack Ferrante and Ferrante’s son Billy jumped into a car to rush to the scene, a neighborhood called Krainwood Shores. The older Ferrante is a firefighter in Arlington, Mass.

Sampson said they found members of the family, including grandparents, parents and two children, on the ground and helped lead them away from the flames.

“It was a huge explosion. The six of them said they were blown from the second floor of the house,” Billy Ferrante said. The group made it to the dock where the injured climbed into a boat.

Sampson, neighbor Peter Ravanis, and one of Sampson’s sons took their boat across the cove and towed the family to the other side.

“The flames must have been 50 to 60 feet in the air,” Ravanis said. “It was so hot on the boat I was ready to jump into the water,” he said of the dockside rescue.

Sampson said members of the family said their youngest daughter was missing.

“The family was just stunned. The mother was yelling for her baby and the father was saying he couldn’t get her. The mother just kept yelling ‘my baby,”‘ Billy Ferrante said.

After getting out of the boat at Sampson’s dock, they went to the Ravanis home where ambulance personnel treated them before taking them to Lakes Region General Hospital. The grandmother appeared to be the most seriously injured with a injured shoulder, Billy Ferrante said.

Kinmond said the blast reduced caused a “tremendous fire” and reduced the home to rubble. Much of the debris blew into the lake.

The destroyed home, like most in the area, was a second home, used mainly for summer weekends, the chief said. He said he assumes the victims were up for the long Memorial Day holiday, traditionally the beginning of the summer boating season.

The property was owned jointly by a father and son, he said, one from New Hampshire, the other from Massachusetts.

Witnesses said two damaged cars were in the driveway Sunday morning, one with New Hampshire plates, the other carrying Massachusetts plates. The fire had melted their tires.

Sampson and neighbor Pat Roth said the initial explosion was followed by a second one as the propane tank in front of the house exploded.

“It made a mushroom cloud,” Roth said.

Sampson said a gas grill appeared to have caused a third, smaller explosion.

Firefighters from four departments were called out to the three-story home.

Moultonborough, population about 4,500, is on the northern shore of Lake Winnipesaukee, New Hampshire’s largest lake. The town is about 40 miles north of Concord.

AP-ES-05-25-03 1826EDT