The road hasn't been closed, however, a stop-go operation is in place. Motorists are being told to expect delays or avoid the area if possible.
A St John spokeswoman said two ambulances were sent to the scene.
Neither the police nor St John could comment if anyone was injured in the crash.
SH35 OMAIO - SERIOUS CRASH - 3.20PM Due to a serious crash just south of Omaio a stop/go is in place. Please pass the incident with care and be prepared for some delays. https://t.co/wO1I6AS5Ni. ^MF pic.twitter.com/mst4QpNxZO
— Waka Kotahi NZTA Waikato/BoP (@WakaKotahiWaiBP) April 16, 2019