Police say the 35-year-old suspect allegedly hit the four children shortly after 7 this morning while they were walking along the road.
The children, aged 14, 7 and 5, were injured in the incident.
Police say three of the children were transferred to CWM Hospital, while one remains admitted at the Valelevu Health Centre.
They say all four children are reported to be in stable condition.
The driver remains in police custody as investigations continue.
