One person is in critical condition after being hit by a truck on State Highway 26.

Emergency services were called to the crash on the highway, between Paeroa and Te Aroha, at 10.45am on Thursday.

Police closed down the road and a rescue helicopter was called in to transport the injured patient to hospital.

A spokesperson for the Auckland Rescue Helicopter Trust says a man in his 50s was hit by a truck while weed-eating on the side of the road.

'A rapid sequence intubation needed to be performed to assist his breathing.

'He was transported to Waikato Hospital in a critical condition.”

Meanwhile, police are investigating an incident where a road worker was hit by a vehicle on SH2, near Turner Road, around 7.30pm.

A police spokesperson says indications from their end is the pedestrian was seriously injured.

"Enquiries into the circumstances of the crash are ongoing."