Autopsy results on Jean Fritz Pierre of Brooklyn, the 16-year-old whose body was pulled from Hessian Lake at Bear Mountain State Park Monday, revealed that he died of accidental drowning, the Rockland County medical examiner's office said.

Pierre had no significant medical conditions and suffered no bodily injuries, according to the medical examiner's office Tuesday. Toxicology tests for drugs and alcohol are pending.

Pierre was on a class trip with 47 other students from the International High School in Prospect Heights when he drowned, according to the New York State Park Police and New York City officials.

At the end of a sweltering day, a few of the students -- including Pierre -- moved away from the rest of the group, said New York City schools chancellor Dennis Walcott. According to published reports, Pierre was seen jumping from a rock into the lake.

"They had a very productive trip until this tragedy happened," Walcott said. "And that's what it was. A tragedy."

Pierre was reported missing about 3 p.m. His body was found by emergency workers from the Stony Point and Thiells fire departments about 3:50, shortly after the rescue crews arrived.

"They were in the water less than a minute," said Ed Geary, a spokesman for the Stony Point Fire Department.

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Pierre was found some 15 feet from the shoreline in a section of the lake that drops off to eight feet, Geary said. Swimming is not permitted in the area where his body was discovered.

It was not immediately clear whether he knew how to swim and authorities have ruled out foul play.

There were five adults supervising the students, according to published reports.

Walcott said the students were under "proper supervision." Nevertheless, the school community is heartbroken, he said.

At Pierre's school on Tuesday, grief counselors were on hand and were scheduled to be available for the rest of the week to help the classmates of the ninth-grader cope.

The school did not return a call for comment.

The investigation into Pierre's death continues.