A prayer service will be held tonight for Mr and Mrs Johnston.
The Johnstons leave behind 10 children aged from 14 to their early 30s. Brian Johnston was a long-serving anaesthetist with the Bay of Plenty District Health Board.
The couple attended Greerton Bible Church for more than 20 years, and their pastor John Elen said many of their congregation are numb from shock, Radio New Zealand reported.
"They had a real passion for serving the God they loved and the people which were entrusted to them. They were involved in so many things and that's why such a wide portion of the community actually know who they are,'' he told Radio New Zealand.
Bethlehem College principal Eoin Crosbie met last night met with parents, relatives and friends of the group.
About seven of the group in Kenya remained in hospital in Kisumu with injuries ranging from superficial to more serious, but none were life threatening, he told Radio New Zealand. A number of Kenyans were also hurt in the crash.
The three deaths were a devastating blow to the tight-knit Bay of Plenty community, he said.
"Brian and Grace were really well known and very committed to the Bethlehem College community ... and Caitlin was very committed to this work."
Similar trips are planned to Tonga and the Solomon Islands later this year.
The school would look at management of risk in other countries, but was committed to continuing the volunteer trips, Mr Crosbie said.
"The value of these trips is just immense and it's life-changing."
New Zealand's deputy high commissioner and consular staff are travelling to Kenya today to provide support and arrangements are being made to bring the group home.
- with Bay of Plenty Times
