Rose McGowan rushed to the aid of an elderly man after he was assaulted in Los Angeles.

She wrote on Twitter: "I just witnessed a 65 year old man get punched by an evil guy playing that goddamn knockout game. #criminal #heartbroken #whattheF?! Evil guy was wearing a mask. (sic)"

Rose, 40, added she had started out after the assailant but couldn't catch him, adding: "He was on a skateboard. Too fast. I chased."

Describing the state of the gentleman who had been attacked, she wrote: "Bleeding from the ear. Called an ambulance for him. His little dog tried to protect. :( (sic)"

A spate of so-called 'Knockout Game' incidents have occurred in the US recently, where young people pick on an unsuspecting older person at random and try to knock them out with a single punch, usually while filming it on a mobile phone.

Authorities have warned against such behaviour and vowed to hand out heavy punishments to anyone caught attempting such a move.

Los Angeles Police Department's Pacific Division has been in touch with Rose to get more details about the incident, but the man responsible has yet to be named or located.