A 36-year-old teacher was found dead Thursday in the bathroom of a Bronx public school after an apparent overdose, a law enforcement source said.

The man, who was not immediately identified, was found in the bathroom at PS X811 on Longfellow Avenue, near Jennings Street, at about 5:55 p.m. He was pronounced dead at the scene, police said.

Investigators found drug paraphernalia and an unknown substance near the man’s body, leading them to believe he overdosed, a source said.

“This is deeply saddening and my heart goes out to the teacher’s family and the school community,” Schools Chancellor Carmen Fariña said in a statement. “We will be providing grief counselors and ongoing resources to support students and staff during this difficult time.”

No students were around at the time of the teacher’s death, a Department of Education spokeswoman said.

The medical examiner will make the official determination of cause of death.