Four New York Police Department (NYPD) officers are being investigated for allegedly beating up a mentally ill man while he was in handcuffs.

The emotionally disturbed patient was being held at Brooklyn's 67th Precinct stationhouse in East Flatbush when EMT workers were called to transport him to a nearby hospital on July 20.

However, when they arrived to the station around 7:30 p.m., the man was combative and banging his head against the wall, states an FDNY report obtained by the New York Daily News. The emotionally disturbed patient also spit on the officers and swore at them.

In response, the cops repeatedly punched him in the face, pulling him off the stretcher to the ground and then tossing him back onto the stretcher.

"Pt. came out of the cell in cuffs. Pt. became combative with PD and (was) put on our stretcher," wrote one EMT in the Unusual Occurrence Report filed with FDNY brass.

"Pt. was struck in the face by an officer ... pt. spit in the face of an officer, whereupon the officer punched the pt. in the face multiple times," the report said.

The cops eventually stopped once the EMTs intervened, the report said.

"Three cops began to punch the patient in the face, EMS (had) to get in the middle of it to intervene. Pt's. wounds and injuries cleaned in the (ambulance)," the report said.

The second EMT noted that the patient was brought out by ESU in "handcuffs and foot shackles" in an FDNY report.

After being punched, the patient was "taken off the stretcher to the ground and restrained again, pt. was thrown by ESU again on to my stretcher," the EMT wrote, adding that the "Pt. sustained injuries to face and head."

An FDNY spokesman confirmed that it received a notification from the agency to the NYPD.

The NYPD also said the incident is being investigated by the Internal Affairs Bureau, reports Reuters.