One person is in critical condition and another seriously injured after a three-vehicle crash near Cambridge.

People were trapped for a time after the crash, which happened on State Highway 1 at 11.30pm on Friday.

A St John spokesperson said this morning that the two injured people were in Waikato Hospital.

A motorist, who was travelling to Ruapehu with her son, said they arrived at the scene just moments after the crash happened.

Advertisement

"It was a very horrible feeling because we were just seconds from being in the crash as well," she said.

The woman, who did not wish to be named, pulled over to help and call emergency services.

"There were people trapped in two of the cars. I rushed to one of the guys who was stuck ... he was in pain. We were talking to him. He was communicating but he was screaming from pain," she said.

"There debris all over the place."

The woman said it was raining at the time of the crash.