Updated 5.17pm
Bethlehem College principal Eoin Crosbie said the driver of the car who was killed was a Kenyan associated with the Ark Quest Academy.
Mr and Mrs Johnston were the parents of a student and Ms Dickson a past student.
"This tragedy will touch the lives of many in this community as these were all wonderful people who served others first as part of their expression of their Christian faith," Mr Crosbie said.
Other people in the van suffered various injuries but it was understood that none are of a life threatening nature.
The group were all together in a private hospital in Kisumu.
Parents of students had all been contacted and were receiving information and support.
Arrangements were being made to bring the group home when this is possible, including those who were killed.
"Caitlin, Grace and Brian had all been to this village before and were passionate about the ministry that was being offered, through building a strong caring Academy in this very needy community. Bethlehem College has been in partnership with Ark Quest School for over two years and has similar partnerships in the Solomon Islands and in Tonga," Mr Crosbie said.
Updated 5.10pm
A dream trip to Kenya has turned to tragedy for students at Tauranga's Bethlehem College after a "grisly"crash claimed the lives of three people.
A group of 12 students from the school, accompanied by seven adults including parents, teachers and a doctor, left New Zealand on December 28 to participate in a four-week volunteer project.
At 11.30am on Tuesday (Kenya time) the volunteers travelling on the Nairobi-Murang'a highway in a car and minivan. It was raining heavily and the van lost control, rolled and ran into a ditch.
The van driver died instantly. Tauranga couple Brian and Grace Johnston and former college pupil Caitlin Dickson were also killed.
A number of other students and adults in the group were injured and are being treated at a private hospital.
A Ministry of Foreign Affairs and Trade spokesperson said the ministry was aware of "a motor vehicle accident in Kenya involving students from Bethlehem College in Tauranga".
"The New Zealand High Commission in Pretoria is providing consular assistance and support. We are unable to release further details at this time."
As news of the tragedy broke this afternoon Bethlehem College staff and families of the 12 students in Africa closed ranks and declined to give any information about what had happened.
It was yet to be confirmed whether those who did not survive died at the crash scene or later in hospital.
Murang'a South traffic boss Loise Gatimu told a local reporter for The Star that the road where the crash happened was notorious for bad driving.
She said most accidents in the region had been caused by careless drivers.
"We are losing too many innocent lives on this road that has turned into a nightmare to residents due to careless driving. The rising carnage can only be checked if drivers observe traffic rules.
"It is sad that we have lost one life," Gatimu said.
In November, some of the students spoke about the upcoming trip - which they were looking forward to.
It was the third time that the college has sent volunteers to the Ark Quest Education Centre, where they were set to spend their time painting, building, teaching, visiting and "generally helping out wherever they are needed".
Before the trip associate principal Phillip Russell told the Bay of Plenty Times that he believed the journey was life-changing for the students involved.
"When we visit Kenya, the students get as much as they give. They come home with a whole new perspective about what's important in life and most get really excited about making a difference here in their own community"he said.
Each student had to raise $5000 to fund their trip, and they had been fundraising for months in the lead up to it.
The college website still had information about the trip last night.
"The team will be based in Ma'hanga Village in the Vihiga District of the Western Province. The team will be involved in improving the school's facilities (painting, making shelves and creating resources). There will be a strong focus on building relationship with the community and being part of village life. Students will also be involved in daily devotions with a clear intention to strengthen their character."
The group were being hosted by the village in a local house and were eating traditional Kenyan food during their stay.
By Anna Leask of the New Zealand Herald
Updated 4.25pm
The victims killed in the Kenyan bus crash have been named. They are Brian and Grace Johnston and former Bethlehem College student Caitlin Dickson from Tauranga.
Updated 3.23pm
Three New Zealanders have been killed in a bus crash in Kenya.
3 News have reported that the trio were involved in a volunteer trip organised by Bethlehem College in Tauranga.
It is understood that the victims are a married couple and a teenager from the school.
The college has a partnership with the Ark Quest Education Centre in Ma'hanga Village, western Kenya.
The school website said students on the next trip to Kenya at the end of 2013 would help with painting and construction to improve the facilities at Ark Quest.
A Ministry of Foreign Affairs and Trade spokesperson said the ministry was aware of a motor vehicle accident in Kenya involving students from Bethlehem College in Tauranga.
"The New Zealand High Commission in Pretoria is providing consular assistance and support. We are unable to release further details at this time.''
African news outlet The Star reported yesterday that the "grisly'' accident happened on the Nairobi-Murang'a highway about 11.30am on Tuesday, local time.
Shortly after the crash it was reported that one person died in the crash and several other "travellers'' were seriously injured and "fighting for life'' at Maragua District hospital.
It is understood the crash occurred when a car collided with a 14-seater matatu - a privately owned minibus.
Murang'a South traffic boss Loise Gatimu told The Star that the car swayed to avoid hitting a pothole and collided head on with the minibus that was heading from Nairobi to Murang'a town.
The driver of the car died instantly.
Passengers in the minibus, understood to be the group from Tauranga, sustained serious injuries and were rushed to hospital.
"It is sad that we have lost one life,'' Ms Gatimu said.
She said most accidents in the region had been caused by careless drivers.
"We are losing too many innocent lives on this road that has turned into a nightmare to residents due to careless driving. The rising carnage can only be checked if drivers observe traffic rules.''
Medics who attended the crash told The Star that others in the crash had sustained "serious'' injuries.
"Some of them are bleeding heavily as a result of the serious injuries,'' a nurse reported.
Earlier:
Three New Zealanders have been killed in a bus crash in Kenya.
3 News have reported the trio were involved in a volunteer trip organised by Bethlehem College in Tauranga.
It is understood the victims were a married couple and a teenager from the school.
The college has a partnership with the Ark Quest Education Centre in Ma'hanga Village, western Kenya.
The school website said students on the next trip to Kenya at the end of 2013 would help with painting and construction to improve the facilities at Ark Quest.
The Ministry of Foreign Affairs and Trade are expected to make a statement on the deaths shortly.
Hint: They are more likely to degrade waterways than mutate into a crime-fighting team.