It has been a day of carnage on New Zealand roads this afternoon after two people have died in separate crashes at opposite ends of the country.

A child was also injured after a collision between a car and school bus in Queenstown and a person was seriously hurt in a crash on State Highway 1 south of Whangarei.

One dead in South Canterbury

One person died and three others suffered injuries after a four-vehicle crash in South Canterbury.

The accident happened on Waimate Highway, State Highway 1, near Morven.

A St John spokesperson confirmed one person was dead in the crash. One person was in a serious condition and two were in a moderate condition.

The seriously injured patient would likely be flown to Dunedin Hospital. The two moderately injured patients were taken to Timaru Hospital.

The state highway has been closed and diversions are in place at the intersections of Barnetts Rd and Hornsnells Rd.

The Serious Crash Unit have been advised.

One dead in Northland

In a separate crash in Northland, a female died after a collision just north of Towai.

Two other people are being treated for moderate injuries.

Sergeant Daniel Cleaver said the crash was near a sharp bend just north of the Towai Tavern.

Traffic was to be detoured onto Akarama Rd then Ruapekapeka Rd.

The diversion was only suitable for cars and light vehicles only. All heavy traffic was to be stopped and would have to wait on the side of the road.

The crash involved multiple vehicles.

At this stage the only available diversion for heavy vehicles is taking the alternate State Highway 15 route from Kaikohe or Whangarei.

The Serious Crash Unit is attending the incident.

A person at the Towai Tavern said he could not quite see the accident as it was just around the corner.

Update: A detour is now in place which will add 2 hours to your journey. Consider delaying unnecessary travel ^LC https://t.co/LuaO4wfDZU pic.twitter.com/2sTQIYKfQn

— NZTA Akld & Nthlnd (@NZTAAkl) November 3, 2017

He had heard the fire siren go off and then traffic started backing up past the tavern. The man had also seen a number of police cars go past.

A few motorists had stopped at the pub to wait for the road to be cleared.

Associate Minister for Transport, Shane Jones said he was horrified to hear of the second fatal car crash on Northland roads in three days.

"It's an awful tragedy and my aroha goes out to all the whanau."

He said whatever the cause of the accidents, questions about the condition of Northland roads would likely arise.

"The robustness of our roads and the need for safety is paramount.

"We need to improve the level of investment and the access to funding to enable the North to improve the most egregious conditions of our roads," Jones said.

Unfortunately the diversion in place following the Towai crash is blocked after a truck has become stuck on the diversion - which was only suitable for light vehicles.

As a result police have set up a longer diversion that will now see traffic diverted through Towai Rd, Callaghan Rd and Maromaku Rd.

"Motorists going travelling through the area will need to exercise patience and factor in the longer travel time through the diversions," police said.

Queenstown school bus crash

One child was injured after a collision between a car and school bus in Queenstown.

A police spokesperson said they were called to the crash on Frankton Rd between Sugar lane and Yewlett Crescent at 3.49pm.

A St John spokesperson said two patients had been transported to Lakes District Hospital.

One patient was a 8-year-old girl with minor injuries, and another patient sustained serious injuries.

Serious injuries south of Whangarei

A person has been seriously hurt in a crash on State Highway 1 at Maungakawera, just south of Whangarei.

Emergency services are at the scene.

A St John ambulance spokeswoman said the incident involved a car and a motorcycle and happened just after 5pm.

One person had serious injuries, she said.

An ambulance is there.