Eight people have been taken to hospital after two serious crashes within four kilometres of each other on Waikato highways.

The first crash happened at the intersection of State Highway 29 and Hopkins Rd around noon on Monday.

Around the same time emergency services were called to a second crash where someone failed to give way a short distance away at Puketutu Rd and State Highway 27.

A St John spokesperson says seven people were transported by road to Waikato Hospital from the SH29 crash.

One was in a critical condition, three were moderate and three people suffered minor injuries.

St John was then called to the second crash on Puketutu Rd at 12.21pm.

One person was airlifted by helicopter to Waikato Hospital in a serious condition, she says.

Diversions are in place and motorists are asked to avoid the area near Matamata if possible.

Two vehicles were involved in the collision at Hopkins Rd and SH29, Fire and Emergency northern communications shift manager Scott Osmond says.

Matamata firefighters on the way to that crash came across the second collision at the SH27 and Puketutu intersection, he says.

The second crash involved a van and left one person trapped in a critical condition.

Tīrau firefighters were then called in to respond to the first crash at the Hobbiton turnoff outside Chookys Auto.

A worker at Chooky's Auto heard the smash.

"It looks like someone has tried to turn into Puketutu Rd and it's been a bit of a head-on.

"All the emergency services are here."

Two ambulances, fire and police were at the scene, he says.

"There's quite a few people sitting on the ground, there's definitely some injuries."

Several motorists stopped at the scene to help the injured, he said, with one person retrieving items, suspected to be medical first aid, from the boot of a car.

"People were definitely pulling over and running over to help."

Both vehicles, described as small hatchbacks, were left on the road but the worker couldn't see the extent of the damage.

He says the road was lined with road cones, which appeared to have slowed the vehicles down.

"Road workers are directing traffic - looks like there's one lane open with stop-go signs."

Aaron Mudgway​, who has lived opposite the crash site for almost a year, said the intersection has been the scene for many serious crashes over the years.

"It's so bad here, and yet they've got all this room to put in a roundabout to slow things down. It's 100km/h through here and it's the signage that ain't good enough.

"You'll hear these trucks on the horns two or three times a day because of close calls.

"They need to change it, or else this is going to keep happening," he says.

Only 4km away, two vehicles were involved in a second crash at the SH27 and Puketutu intersection.

"It looks like someone has failed to give way at this point, and we have one injured occupant from the van who has been transported to hospital via helicopter," Waikato Police Sergeant Andrew Osborn says.

Nine police staff were on the scene and Osborn said traffic diversions could be in place for some time yet.

"Be mindful, it's going to be a few more hours at each end," he said. "It's hard to say for how long until we complete our investigation."

In 2016 a woman died and two others were critically injured when a logging truck and a carload of tourists collided at the Hobbiton turnoff.

The car had turned directly into the path of the logging truck, police says.

"There always looks to be fresh damage around the intersection over the weekends when we're not open - but we have a lot of near-misses.

"Even today we heard three or four people toot their horn when pulling out."

A stop sign had been installed at the intersection but "some people just drive straight through it".

"You can't miss it."

Helicopters had responded to both crashes where two patients were in a critical condition.

-Stuff/Phillipa Yalden and Kelley Tantau