Jeremy Renner was trying to save his nephew from harm when he was run over by his snowplough on 1 January.
The Marvel actor was rushed to hospital on New Year's Day after suffering blunt chest trauma and orthopaedic injuries in an accident involving his personal snowplough near his home in Reno, Nevada.
According to a redacted Washoe County Sheriff's Office report obtained by CNN, Renner used his PistenBully machine, which runs on a track, to pull his grown nephew's truck out of the snow. After towing the vehicle to a street, the snowplough began "sliding sideways" down a hill, at which point Renner jumped out of his PistenBully to save his nephew.
"Once he was off the Pistenbully, he realized it was heading directly toward (his nephew)," the report reads. "He feared the Pistenbully was going to hit (his nephew), so he decided to attempt to stop or divert the Pistenbully."
The 52-year-old had to climb onto the vehicle's moving track to re-enter the cab, and he was "pulled under the vehicle by the track and run over".
"The Pistenbully rolled over him and continued down the road," the report continued. "He laid on the ground and focused on his breathing while (his nephew and others) rendered aid to him until medical personnel arrived on (the) scene."
In the report, officials noted that the machinery had some "mechanical issues" but they believe it would have stopped moving if Renner had applied the emergency brake upon his exit. However, the brake indicator light inside the cab was not working and "mechanical issues may have been a factor in this accident".
Renner, who suffered more than 30 broken bones in the incident, is now recovering at home with his family.