Police made a grisly discovery inside a reeking, junk-crammed old school bus in Queens on Friday morning — the body of a man who may have been living on board, officials and neighbors said.

The unidentified body was found inside the dilapidated, green-painted bus parked on 177th Street and Liberty Avenue in Jamaica after passers-by reported a foul smell coming from the vehicle and blood collecting underneath it, they said.

The vehicle, which had Virginia plates and was at one time used to sell El Salvadoran food, was crawling with maggots and flies.

Neighbors said the bus had been parked there for at least two weeks.

“What I noticed at first was the stench. It was really, really horrible,” said neighbor Tre Young, 24.

“I thought it was a dead animal or rats.”

“It took them a couple of hours to get inside the bus” due to it being crammed with trash, he said.  “Then more police came with equipment and took the side of the bus off.”

“They took out the dead body, and the stench increased drastically,” he said.

“People has been going inside the bus at night for shelter.”

The Medical Examiner’s Office will determine the cause of death, officials said.