An FDNY firefighter allegedly punched an on-duty NYPD police officer in the face while suffering a mental health crisis inside a Queens hospital this week, prosecutors and sources said.

Firefighter Abel Sencion, 34, was on duty Wednesday night when he experienced the crisis and was taken to the Queens Hospital Center, the sources said.

During his time at the hospital, Sencion allegedly slugged 32-year-old Officer Philip Vallon in the face just before 10 p.m., according to a criminal complaint.

The blow left the officer with redness, swelling, and substantial pain, and he stayed at the hospital for treatment, the court doc said.

The attack was unprovoked, and the cop and firefighter did not know each other, the sources said.

Sencion was arrested a short time later and charged with second-degree assault, a felony, authorities said.

He was arraigned Thursday by Judge Glenda Hernandez, who set bail at $5,000 cash or $10,000 bond and ordered him to reappear in court June 2.

Sencion will be suspended by the FDNY pending the end to his medical leave, a department spokesperson said. 

Vallon joined the NYPD in 2018 and has been assigned to the 105th Precinct since 2020, according to department records.

Just a week before the attack, he was honored by the Queens Borough President’s Office during a Haitian Flag Day celebration “for his dedication and service to the Queens community,” the precinct posted on X.