Three American students killed in a New Zealand road accident on Saturday have been remembered with emotional tributes.

Boston University students Daniela Rosanna Lekhno, 20, Roch Jauberty and Austin Brashears, both 21, died when the van they were in got out of control on the way to the Tongariro Crossing walk in the North Island.

The students were just over a month away from finishing their exchange studies at Auckland University and wanted to see where the Lord of the Rings was filmed.

About 200 people attended a student-organised candlelight vigil in Boston on Saturday night, US time.

Mr Brashears' girlfriend, Tori Pinheiro, fought tears as she spoke at the vigil.

"You were the love of my life and we made each other so happy ... and I have never experienced a joy like I had with you."

Mr Brashears' father, Thomas, told One News his family was devastated by the loss of "a special young man".

"He squeezed every ounce of excitement and energy and enthusiasm out of life. He's a light in our lives that we're going to really miss," he said.

"The only thing that we've really been able to find any solace in at all is that everything that Austin did, he did top notch, he did his best."

He was still deciding whether to come to New Zealand to accompany his son's body home.

Austin Brashears had wanted to come to New Zealand since his younger sister took part in a surf lifesaving exchange at Piha, Mr Brashears said.

The students were among 49 from Boston University on exchange in Auckland, and 26 travelled to the Tongariro Crossing in three vans.

Another student, Margaret Theriault, 21, who was studying in Sydney, remains in a critical condition in intensive care at Waikato Hospital, while Kathryn Moldawer, 21, and Alys McAlpine, 20, were in a stable condition in Rotorua Hospital.

Two other students were treated at Taupo Hospital and discharged following the crash, and most of the group returned to Auckland University on Sunday.

The university says the students have been offered counselling and it is likely a memorial service will take place.

The driver of the crashed van is reported to have survived, but it is not yet known whether they will face charges.