Police said they arrived at the scene around 4:30pm on State Highway 29, Kaimai Ranges, Tauranga.
A Nissan vehicle travelling west crossed the centre line on a bend and collided head on with two cars travelling in the opposite direction, police said.
The nine-year-old girl was in the back seat of a Subaru, and died at the scene.
Four other occupants of the Subaru were taken to Waikato Hospital by ambulance with serious injuries, police said.
The driver and passenger of the Honda car sustained moderate injuries. The driver of the Nissan was taken to Tauranga Hospital in a serious condition.
Traffic diversion were in place on either side of the Kaimai Ranges. SH29 was reopened three hours later at 9:30pm.
Police are investigating the crash.
