Jeremy Renner was injured while trying to rescue his nephew and the parking brake on the snowplow may not have been properly applied, according to a police report on the Jan. 1 accident obtained by The Hollywood Reporter.

The report states that as Renner was clearing snow on New Year’s Day, the Avengers star was run over by his PistenBully snowplow as he was trying to divert it away from his nephew.

“In an attempt to keep the Pistenbully from striking [his nephew], [Renner] attempted to step up on the track in order to divert the Pistenbully or get it stopped,” the report from the Washoe County Sheriff’s Department states.

Renner instead was pulled under the snowplow, where he sustained major injuries, while his nephew escaped harm and was able to help his uncle until emergency first responders arrived.

The police report concluded that the emergency brake on the snowplow had not been properly applied as Renner exited the vehicle, which contributed to the accident. “Although the Pistenbully had some mechanical issues, it is believed based on our mechanical inspection that the parking brake would keep the Pistenbully from moving forward,” the report states.

During a Jan. 3 news conference, Washoe Sheriff Darin Balaam called what happened to Renner a “tragic accident” and noted no foul play was suspected but that an investigation into any potential mechanical failure of the snowplow was being conducted.

The evening before Renner’s accident, the area had received approximately three feet of snow, which also delayed the emergency response, due to poor conditions and a local highway being closed.

Once responders reached Renner, he was flown to a Reno-area hospital and treated for chest trauma and orthopedic injuries. The actor underwent surgery the day after the accident and was later admitted to the hospital’s intensive care unit in critical but stable condition.

On the same day as the news conference, Renner posted an update from his hospital bed to his social media. “Thank you all for your kind words,” the actor wrote. “Im too messed up now to type. But I send love to you all.”