One woman has died and another is in a critical condition after a car accident in Waikato.

District Road Policing Manager, Inspector Leo Tooman, said the smash happened on Old Taupiri Rd near Ngaruawahia about 6.15 tonight, and is being investigated by the Waikato Serious Crash Unit.

"Initial indications are a northbound Subaru Impreza has failed to negotiate a bend and smashed through a fence.

"A woman ... passenger in the car suffered critical injuries ... while a male adult passenger suffered minor injuries,'' Mr Tooman said.


"Two boys, believed to be aged five and seven-years-old, were taken to Waikato Hospital by ambulance suffering from what was described as minor to moderate injuries.''

Mr Tooman said the SPCA has also been called to the scene to deal with a puppy injured in the crash.

"At this stage it is far too early to determine the cause of the crash but we are investigating what, if any part, speed and alcohol played in what happened.''

Emergency services were clearing the wreckage.