State Highway 2 between Gisborne and Wairoa will be closed at some point over next two days for fatal crash investigation

Police will close State Highway 2 between Gisborne and Wairoa at some point over the next two days to investigate a fatal bus crash.

Tongans Talita Fifita, 33, and Sione Taumololo, 11, died when the bus they were in crashed 100m down a Hawke's Bay bank on Christmas Eve.

There were 53 people on board when it crashed. Ten are still in hospital. The bus was carrying a brass band from Mailefihi Siuʻilikutapu College in Tonga, who were touring New Zealand as part of a fundraiser.

Reverend Sunia Ha'unga, of the Tongan Wesley Methodist Parish in Gisborne, said survivors had told him the brakes on the bus failed.

"They said the driver was trying and trying to stop, but the brakes weren't working."

Police will advise when the road will be closed on the Eastern District Police Facebook page.

The investigation will include a full mechanical inspection of the bus once it is recovered, along with an assessment of road conditions and any other possible contributing factors .

Police are speaking to several people who were on the bus, including the driver. Interviews are expected to take two days.

"This crash is a tragedy for all those involved and we are offering all the support we can to the passengers as they grieve and mourn the loss of their friends and loved ones," Tairawhiti area commander Inspector Sam Aberahama said.

Police were unable to speculate the cause of the crash while the investigation was continuing.