Footage has revealed Tribesmen gang members driving recklessly into oncoming traffic and illegally driving on the wrong side of the road.
A witness claims to have seen a group of about 80 gang riders at Karapiro, nearly crashing while pushing motorists over to pass.
"They tried to force me off the road but I held my line. I will not be intimidated," the witness said.
"They took evasive action to the opposite side of the road and continued into oncoming traffic at high speed."
It is understood the Tribesmen were returning to Auckland from Taupō where they had been meeting with other members from across the country.
A motorist was critically hurt on the Waikato Expressway after reportedly being dragged from his vehicle and attacked in an incident involving a convoy of gang members on motorbikes.
The motorist is in a stable condition, but a police investigation continues.
A witness told the Herald they saw about 30-40 motorcycles "roaring past at a ridiculous speed".
"As I was driving past the Rangiriri exit, we had to brake so suddenly," Belinda Williams said.
"There was an individual who ran across the southbound traffic lane, causing us to brake to avoid [collision with] him, and trucks and other vehicles."
The man was said to be running from a white ute travelling south.
"Everyone swerved to avoid him. He was shirtless."
"We drove past a red ute which was stationary with a smashed windscreen and a person was laying on the ground with wounds."
Another witness, Ian Erasmus, was travelling towards Taupō when the large group of Tribesmen drove past him in the opposite direction.
"This group were by no means following the rules of the road.
"Several times whilst going past the convoy of bikes in the opposite direction, I was forced to brake heavily to avoid a head-on collision as they overtook vehicles in front of them.
"It was scary, given the reckless driving and the fact that there were so many of them blatantly driving like total idiots.
"Obviously, they couldn't give a hoot about others or themselves on the road.
"We noticed a short time after, trailing behind them was a single white police Holden wagon, no lights or sirens, obviously aware of the transgressions but hopelessly outgunned and powerless to do anything but watch."
Police said last night they had begun investigating an incident "that has left a man in a critical condition".
"Police were called about 4.45pm to the expressway south of Rangiriri following multiple reports of an altercation involving several people and vehicles, including a significant number of motorcycles," a police spokeswoman said.
"Initial indications suggest that during the incident a man was pulled from a vehicle and assaulted."
Police are looking to hear from anyone who witnessed the incident or anyone who might have dashcam footage or cellphone footage that could assist their inquiries.
"If you can help, please call 105 and quote event number P049885631.
"You can also call Crime Stoppers on 0800 555 111."
Wayne Dewes died in hospital from severe injuries.