An elderly woman was doing early morning deliveries in Hamilton when a group of teenagers flagged her down, dragged her out and stole her car.

The incident began in Nawton on Wednesday about 5.40am, Detective Sergeant Nick O'Brien of the Hamilton CIB said.

"An elderly woman was doing deliveries in her black Toyota hatchback when she was flagged down by four people who asked her for the time.

"The group which was made up of teenage males and females then dragged the woman out of her car and sped off along Avalon Dr."

The group then drove to Raglan where a moment's inattention resulted in another woman losing her car, O'Brien said.

"The offenders have arrived and noticed a woman leave the keys in her car when she parked her Skoda Octavia on the main street and went into a bank.

"Two of the offenders got out of the Toyota and into the Skoda and both cars headed back to Hamilton via State Highway 23 however they were intercepted by police. After a short pursuit both cars were stopped and the offenders apprehended."

O'Brien said one male and one female appeared in the Hamilton Youth Court on Wednesday in connection with the thefts while a woman was due appear in the Hamilton District Court on Thursday.

A fourth woman will appear in the district court next week.

O'Brien said there were some lessons that could be learnt from the incidents.

"While it was pretty good to be able to return the first victim's car to her relatively unscathed we have some concerns we want to raise with the parents of the four teenagers around their access to alcohol and supervision.

"The other issue is we're asking that drivers avoid leaving their cars unlocked with the keys in it.

"Our message around valuables in cars, and the vehicles themselves, is lock them or lose them."

The victims have declined to be interviewed.