Police say a driver who died after colliding with a school bus in south Taranaki may have veered onto the wrong side of the road.
A six-year-old girl was airlifted to Wellington Hospital following the collision and remained in a serious condition in intensive care on Tuesday morning.
The dead woman has been named as Larissa Amelie Sirch, 20, from Germany, who had been working in Taranaki.
Hawera volunteer brigade chief Darryl Fowler says it appears the car and the bus collided head-on at Manutahi, about 20km south of Hawera, on State Highway 3 at 3.40pm on Monday.
The front of the car was wedged underneath the bus, which was carrying about 30 students from Hawera Intermediate and Hawera High.
Mr Fowler says firefighters used the jaws of life to remove the top of the car to rescue the girl from the back seat.
The bus driver and one student were taken to Hawera Hospital with minor injuries.
A Hawera sergeant at the scene, Ivan Smith, says several people witnessed the accident including an off-duty police officer.
He says it looks as though the north-bound car strayed into the opposite lane, although investigations are continuing.
The Serious Cash Unit is inspecting both vehicles and the road conditions as part of its investigation.
Acting Taranaki area commander Inspector Frank Grant says while those on the bus did not have serious injuries they are badly shaken up.
On Twitter, bus passenger Emma Watson said she was flung face first into the seat in front of her. She said the young passengers were screaming and crying.
Radio New Zealand's reporter says the top of the car was ripped away by the impact. She says the crash happened at the start of a passing lane at the top of a hill.
The highway was closed for several hours and drivers diverted about 10km around side roads.
The bus company, Weir Brothers, says its driver was shaken and it sent a second bus to collect the children.
It says the driver is taking some time off and the company is working closely with the schools involved to reassure those worried about safety.
The school bus service was running as normal on Tuesday.
Hawera Intermediate principal Craig Simpson says it was frightening when the bus company notified him.
"I was just hoping everybody was safe," he told Radio New Zealand. "They reassured me that all the students were safe and were being transferred to another bus."
Hawera High principal Hans Konlechner said the deputy principal had rung students' families on Monday and students were expected to return to class on Tuesday.