Police are hoping to track the movements of a Subaru Legacy and a red-coloured Mazda sedan which may be linked to a fire on the Tinakori Rd off-ramp yesterday.
Police said the vehicles were at the centre of an incident which began about 11.45am on State Highway 1 near the Basin Reserve.
They said the cars travelled together through the Terrace Tunnel and came to a stop on the Tinakori Rd off-ramp just after noon.
At about this time, Police received reports the Subaru Legacy was on fire.
Two people were arrested.