A woman giving birth has been caught up in an Auckland tornado.

It hit East Tamaki around nine o'clock this morning, tearing roofs off homes and businesses, and blowing an outside wall off Elite Bathroomware, leaving a pile of debris on the ground.

Fire and Emergency shift manager Craig Dally says a woman was giving birth in the back of an ambulance in Franklyne Road in Otara when the tornado came through and struck a shed.

He says the shed was pushed against the ambulance, breaking the windows.

Dally says firefighters helped out by making the area safe and clearing the debris.

St John Ambulance says the woman has been taken to Middlemore Hospital in another ambulance, in a moderate condition.

Dally says another tornado has hit a small area of Papamoa Beach in Tauranga.

He says Fire and Emergency received about ten calls about houses with roofs lifting or tiles blown off.

Dally says there are still a few trucks in the area dealing with that.