A student at a New Jersey elementary school plunged to his death from a second-story window in what police are investigating as a suicide, a law enforcement source familiar with the case tells NBC 4 New York.

The boy, in fifth grade at Grant Elementary School in Dumont, was initially taken to a hospital in critical condition after the jump around noon Friday, authorities say. The source said he later died at Hackensack University Medical Center later in the afternoon.

A law enforcement source said the boy got into a dispute with a classmate during a game of chess. Afterward, the boy passed his classmate a note, then went to the window, opened it and jumped, the source said.

Schools superintendent Emmanuel Triggiano said there were other students in the classroom at the time.

"We provided them with some assistance, and we're going to continue to provide them with assistance through the weekend and on Monday," said Triggiano.

The school had a regular dismissal, but some parents took their children out early.

A portion of the building was taped off as police investigated.