A man who caught two people breaking into his van early this morning was taken to hospital after an altercation that also left one of the alleged thieves with a life-threatening injury.
Police were called just after 4am to a vehicle break-in on Te Atatu Rd in West Auckland, close to the northwestern motorway.
A spokeswoman said a person reported two men were breaking into his vehicle.
After an altercation the alleged thief and van owner were taken hospital.
Police want to talk to witnesses and said the alleged thief remains in a critical condition.
The van owner has since been discharged.
"While it was initially reported he had sustained a head injury, it is not clear at this stage what caused the [alleged offender's] loss of consciousness."
No charges have been laid and no one has been arrested, police said, but a guard is at the scene+.
A St John spokeswoman said one person was taken to Auckland Hospital in a critical condition and another to Waitakere Hospital in a moderate condition.
Emergency services could not tell the Herald whether the second person was injured or had suffered a medical event.
A person at the scene said two police cars were still there about6am. An orange sports shoe and a bloodied towel or sheet was in the driveway, he said.
Police are still making inquiries and looking for the other person involved.