A 20-year-old man was decapitated by an oncoming F train in Carroll Gardens this morning, according to police. Witnesses say he put his head on the tracks, and the NYPD is treating the incident as a suicide.

The NYPD says an F train operator spotted the man with his head on the tracks at the F train station at Smith and Ninth Streets at around 2:40 a.m. this morning. Police say the operator attempted to stop the train, but it was too late.

Though the NYPD has not released the victim's name, the NY Post has identified him.

If someone you know exhibits warning signs of suicide: do not leave the person alone; remove any firearms, alcohol, drugs or sharp objects that could be used in a suicide attempt; and call the U.S. National Suicide Prevention Lifeline at 800-273-TALK (8255) or take the person to an emergency room or seek help from a medical or mental health professional.