A man has been seriously injured after confronting a group of youths attempting to steal his vehicle in the Christchurch suburb of Avonhead.

A police spokesperson told chrislynchmedia.com police were alerted to an assault and vehicle theft on Hawkswood Place at approximately 10.30pm on Friday.

Chris Lynch Media understands the resident was attacked with a metal bar by one of the youths, who is believed to be known to police.

The offenders fled the scene before officers arrived.

A St John spokesperson told chrislynchmedia.com an ambulance responded to the incident.

Ambulance staff treated one patient at the scene before transporting him to Christchurch Hospital in a serious condition.

No arrests had been made.