The petrified woman was squashed up against the rear window as the front end of the BMW was rapidly submerging into the Waitemata Harbour in Auckland at 3pm on Tuesday.

Fortunately witnesses called emergency services as quick-thinking policemen arrived and sprung straight into action by jumping into the water. 

The officers and a bystander couldn't open the doors so one officer attempted to smash the window with a baton with no luck.

Once it became clear that it was not going to penetrate through the glass another officer was handed a rock and managed to shatter the rear window.

The relieved woman was then pulled to safety by the two heroic policemen. 

Detective Sergeant Callum McNeill said police were still trying to work out how the bizarre incident occurred.

He said the woman, who was naturally in shock, got away with just a 'few cuts and bruises and is lucky to be alive,' stuff.co.nz reported.

Erwin Kampos saw the BMW go straight into the drink after driving over the Northcote Point Ferry Terminal's car park rock wall while he was fishing and immediately went into the water to attempt to smash the window. 

'The two police officers smashed the back windscreen, I tried to smash the sides and they didn't want to break. We were running out of time because the vehicle was filling up,' he said.

Another witness saw the car was 'filling up fast' and said the officers got to the woman 'just in the nick of time.' 

(dailymail.co.uk)