Kevin Hart is in a grueling stage of recovery right now after doctors repaired THREE fractures to his spine. He suffered in his horrific Labor Day weekend car accident.

Axar.az reports citing TMZ that sources with direct knowledge said Kevin's Sunday night surgery involved fusing the fractures ... 2 of them in the thoracic section of his spine, and 1 in the lumbar. Although the procedure was a success, Kevin is still going through hell. We're told he has to be heavily medicated because the pain is just that intense.

That being said, it could have been much worse. Lumbar fractures can often result in at least difficulties walking, and at worst ... partial paralysis of the arms or legs. Luckily for Kevin, we're told doctors expect him to make a full recovery, but it's gonna be a long road back.

The eyewitness who called 911 from the accident scene says he saw a security guard pull Kevin from the driver's side window of the wrecked muscle car. CHP says first responders found Jared pinned in the driver's seat when they arrived.

He and his fiancee, Rebecca, were removed after firefighters sawed off the roof of the car. Jared's condition is still unclear, but we're told he suffered similar injuries to Kevin.