Police, emergency services and roading contractors continue to work at the scene, and hope to reopen the road about 3pm.
Police said diversions were in place northbound at Ongaroto Rd and southbound at Campbell Rd.
A witness who arrived at the scene after the crash said the truck and car were at the side of the road.
The car was "pretty munted", he said.
The witness did not know if it had been a head-on collision.
The stretch of road was a "black spot" and there had been previous serious crashes in the area, the witness said.
Ambulances had left the scene and police were at the crash site.
Tokoroa Golf Course acting manager Jon Welch thought the crash was a few kilometres past where he was.
He'd seen emergency services dash past a wee while ago, but could no longer see or hear anything from where he was.
"I saw a couple of ambulances and at least one fire unit," he said.
"One of our members called in and said traffic is being diverted at the moment.
"No traffic is going north or south."
Truck driver Jono Mac, who was stuck at the scene, told the Rotorua Daily Post he was on his way to Kinleith before he got stopped.
"But there's nothing we can do about it. It is what it is. We've been waiting about an hour," Mac said.