New Zealand's police say they will investigate how a father vanished into forest with his three children for years without detection, even as law enforcement expanded a search for them.

A New Zealand father who had been on the run with his three children for nearly four years was shot dead by police on Monday and the children are all safe in custody, police said.

A man who evaded authorities with his three children in the remote New Zealand countryside for nearly four years was shot and killed by a police officer Monday, law enforcement said. One child was with Tom Phillips at the time of the confrontation and the other two children were found in the forest hours after the shoot-out,