An elderly man has been injured and about 20 cars trapped when the hillside collapsed on State Highway Two near rain-soaked Gisborne this afternoon.

One of the two slips pushed two cars together leaving the man with suspected back injuries, Senior Sergeant Mick Lander said.

It was not clear how many people had been trapped but everyone had been evacuated to a nearby fire station by police and volunteer firefighters.

An ambulance had been dispatched from Opotiki as the road from Gisborne was closed because of surface flooding.

A helicopter was not able to reach the danger area because of atrocious wet and windy weather conditions, Mr Lander said.

The highway was expected to be closed until tomorrow morning while workers clear the road.

– NZPA