WAMEGO, Kan. (AP) _ An explosion possibly caused by fireworks shoved a house two to three feet off its foundation early Sunday and injured 11 people attending a party, one critically, authorities said.

''The front door was blown off its frame, the back of the house was pushed out a little bit, there is no plaster left on the living room walls or ceiling,'' said Wamego police dispatcher Norman Spain. ''It's just pretty well demolished.''

Spain did not identify the explosive material, but Pottawatomie County Sheriff's Investigator Gerald Schmidt said fireworks might have caused the 4 a.m. blast.

The victims ranged in age from 18 to 30, and many suffered broken ear drums or ear damage, Schmidt said.

Five people were hospitalized, including one whose arms had to be amputated from the elbows down, and six people were treated at hospitals and released, authorities said.

Agents from the U.S. Bureau of Alcohol, Tobacco and Firearms were called to the northeast Kansas town and an Army explosives detachment unit from Fort Riley was summoned to examine a ''highly volatile substance'' found in the house, Spain said.

The blast left a white residue throughout the four-room house, which was moved about two to three feet from its foundation, said Schmidt. Several cars on an adjacent street also were damaged by the explosion, he said.

Authorities initially thought the explosion was caused by a natural gas leak, but dismissed that possibility because of the residue, said Police Chief Ken Seger. He added that the blast originated in the living room away from any gas appliance.

One man was in critical condition at the University of Kansas Medical Center in Kansas City, Kan., and another man was taken to Stormont-Vail Hospital in Topeka with serious injuries, Schmidt said.