A 30-year-old man involved in a head-on collision south of Thames on Wednesday morning was trapped inside his vehicle for 30 minutes.

Four people suffered multiple injuries following the two vehicle crash which took place on the Paeroa-Kopu Rd /State Highway 26 near the intersection with Omahu Valley Rd just after 10am.

Four people suffered multiple injuries following a two car head-on collision on the Paeroa-Kopu Rd/State Highway on Wednesday morning. 26 Photos: ARHT

The Auckland Rescue Helicopter Trust dispatched both its helicopters to the scene of the crash after being advised two patients were in a serious condition and two patients were in a moderate condition.

The Westpac Two rescue helicopter was the first to arrive at about 10.35am.

'At the scene, St John ambulance staff were extricating the driver of one vehicle, a male patient in his 30's, who had been trapped for approximately 30 minutes,” the trust says.

A 30-year-old man was trapped inside his vehicle for 30 minutes following Wednesday's crash. Photo: ARHT

The crew of the Westpac Two rescue helicopter took over treatment and airlifted him to Waikato Hospital in a serious condition.

The trust says the Westpac One rescue helicopter then arrived at the scene about 20 minutes later.

'On arrival a female passenger, in her 20's, was being treated by St John Ambulance. She had been a rear seat passenger and had managed to get herself out of the car.

'Westpac One crew took over treatment and transported her to Waikato Hospital in a serious condition suffering multiple injuries.”

The Auckland Rescue Helicopter Trust dispatched both its rescue helicopters to Wednesday morning's crash. Photo: ARHT