Emergency services are at the scene of a serious crash on SH4 in Manunui in the Ruapehu District after a car appears to have gone under a truck, trapping occupants.

A police media spokesperson said initial reports indicate a car had slid under a truck on SH4 between Mahoe Rd and Tanoa St just after 6pm.

One person has serious injuries, a police statement said.

Police were at the scene and Fire and Emergency NZ are working to free those trapped.

A St John spokesperson said two ambulances are in attendance and the rescue helicopter has been stood down.

The road between Mahoe Rd and Tanoa St is blocked.