Four people suffered serious burns when a fire pit exploded on Long Island, police said. The explosion happened just before 7 p.m. Saturday at a house in Bridgehampton, the Southampton Town Police Department said in a news release. A man and a woman were airlifted to the burn unit at Stony Brook University Hospital in serious condition, police said. Two other women were taken to another hospital for treatment. A witness told the the East Hampton Star that the explosion occurred during an engagement party. Police and fire marshals are investigating the cause.