Renner, best known for playing Hawkeye in the Marvel Avengers movies - is recovering after being run over by a snowplow that weighed 14,000 pounds.
His publicist said he "suffered blunt chest trauma and orthopedic injuries", and was in critical but stable condition.
Law enforcement in Washoe County, Nevada, where he owns a home, don't suspect foul play.
They say Renner tried to dig out his car on New Year's Day, when the accident happened.
"After successfully towing his personal vehicle from its stuck location, Mr. Renner got out of his pistenbully to speak to a family member. At this point, it's observed that the pistenbully started to roll. In an effort to stop the rolling pistenbully, Mr Renner attempts to get back into the driver's seat of the pistenbully. Based on our investigation, it's at this point that Mr Renner is run over by the pistenbully."
"It has a park and so like we would because, uh, this having severe injuries, we want to make sure that with that mechanical machine that, was there any mechanical failure, had he put it in park--whatever."
The 51-year-old actor was treated in a hospital in Nevada - the area he's lived for years, which was hit by a severe snowstorm over the weekend.
Renner was nominated for an Academy Award for the 2008 film "The Hurt Locker".
He's gone on to star in several Marvel projects, two "Mission: Impossible" films, "Arrival", and "American Hustle", among others.
