Ryan Dunn death mourned by 'Jackass' co-stars

Johnny Knoxville and Steve-O have opened up about the loss of their Jackass co-star Ryan Dunn.

Dunn and a fellow passenger were killed in a car crash in the early hours of Monday morning. Knoxville tweeted his response to the news, expressing his sympathy for Dunn's family.

"Today I lost my brother, Ryan Dunn. My heart goes out to his family and his beloved Angie," Knoxville wrote. "RIP Ryan. I love you buddy."

Steve-O tweeted: "I don't know what to say, except I love Ryan Dunn and I'm really going to miss him."

Jackass co-star Wee-Man - Jason Acuna - also responded to the news via Twitter, writing: "I miss you, bud. You were always a happy kick-ass dude!"

Dave England, who also appeared on the MTV show, posted: "I love you Ryan. I'm gonna miss you bad."

Police confirmed that Dunn was behind the wheel before his fatal crash this morning, stating that speed may have been a contributing factor in the accident.

It remains unclear whether alcohol was involved, though the actor tweeted a picture of himself drinking in the hours before the accident. In addition, TMZ reports that Dunn had consumed three beers and three shots in a Philadelphia bar, though his friends stated that he was "not too drunk to drive".

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Watch a clip of Ryan Dunn and the Jackass crew below: