After the group left, the pair were able to retrieve their keys and drove to Rotorua Hospital.
The woman was not harmed but the man needed stitches to a cut to his head.
Police were still working with the victims to obtain more details and to identify the exact location of the robbery. The van was also being examined.
"I am sure the community of Rotorua is as keen as I am to make sure that these offenders are arrested at the earliest opportunity," Detective Senior Sergeant Zane Smith said.
Police appealed for anyone with information to come forward.