AN American teenager on his way to a Sweet 16 party has been killed after putting his head out of the emergency hatch of a double-decker bus and hitting the underside of a New Jersey highway overpass.

The 16-year-old was among 65 teenagers aboard the bus on Friday night as it crossed the George Washington Bridge from New York City, said Al Della Fave, spokesman for the Port Authority of New York and New Jersey.

The accident occurred at the Fletcher Avenue overpass of Interstate 95 in the early evening.

A security guard on the bus, Alex Franco, said he had warned the teenagers to leave the hatch alone.

“I told them not to open the hatch, like three or four times, but kids, they don’t understand,” Franco told the New York Daily News.

Franco said he went downstairs to tell the driver that it was getting too hot.

“It was very hot,” he said.

“Everybody was dancing. Two, five minutes I was downstairs. Then I heard two guys screaming, ‘Oh, my God, oh, my God.'”

The teenager was pronounced dead at a hospital, police said.