Three vehicles were found in flames in a Pāpāmoa East street early this morning.
Both police and Fire and Emergency have labelled the incident "suspicious" and launched investigations.
Firefighters were called to the fires in Kanapa Close, Papamoa East at 2.37am, with police called to assist about 20 minutes later.
Fire and Emergency Northern Communications shift manager Craig Dally said a fire investigator was looking into the incident.
A police media spokesman said a scene guard was in place from 5am. Police were making inquiries.