An FDNY medic was run over and killed with her own ambulance in the Bronx on Thursday when a man who had been joyriding on the rear bumper commandeered the vehicle.

EMT Yadira Arroyo, a mom of five, was crushed under the wheels and her partner was injured after they tried to shoo the man off the back of the ambulance on White Plains Road at about 7 p.m., according to law enforcement sources.

“They were screaming. They were crying. Everyone was trying to help,” said witness Virgilio German.

The incident began when the EMTs were responding to a call and a passing motorist alerted them that the man was riding on the bumper near Watson Avenue, officials said.

When Arroyo, 44, and partner Monique Williams got out to confront him, he powered past them, hopped into the vehicle and started to drive off, the sources said.

“They were acting very bravely. They certainly wanted to continue on their way to the call. This person had no business being in this ambulance,” Fire Commissioner Daniel Nigro said.

Arroyo tried to stop him, clinging to the side of the ambulance as the 25-year-old man floored the gas pedal, backed into her then dragged her 8 to 10 feet forward, according to witnesses.

A video of the incident posted on social media shows what appears to be the vehicle rolling over ­Arroyo, a 14-year FDNY veteran.

“I heard somebody crying and then I heard, ‘Boom!’ like an accident,” German said. “There were two paramedics. They were down on the floor. She wasn’t moving.”

The video shows the ambulance veering wildly with the driver’s door wide open.

The thief got only a short distance before hitting a car and stopping on Watson Avenue.

Williams suffered cuts and bruises.

The suspect, whose name was not immediately released, has a prior criminal record. He was apprehended by passing MTA K-9 Officer Danny McCabe and a group of good Samaritans.

A second video shows Arroyo motionless on the pavement as a woman — who sources said appears to be Williams — leans over her.

The partner screams in anguish and then darts over to where the suspect is being held down. She apparently gives him a few kicks before being pulled away.

“Makes sense, the guy just ran over her partner,” an FDNY source said. “Wouldn’t blame her for wanting to kick his ass.”

Arroyo was pronounced dead at Jacobi Medical Center, sources said.

“It’s a sad night for everyone in the department,” said Nigro.

Additional reporting by Gina ­Diadone, Carroll Alvarado and Joe Tacopino