Update,. 4.30pm A motorist on the Matamata side of the Kaimai Range says that traffic is still backed up following a crash involving a car colliding with a campervan.

The campervan is reported to have rolled onto its side with those involved only receiving minor injuries.

"[A] Police car just drove past on loud speaker telling everyone 'serious crash sorry for delays'," says the motorist.

"[And] that they are looking at opening one lane shortly. Traffic backed up - we are on the Matamata side."

Police say that they received a report at 3pm that a car had collided with a campervan on SH 29, between McLaren Falls Road and Ngamuwahine Road.

"Expect delays in the area and pass the scene with care," says an NZTA spokesperson.

Update, 3.51pm: Traffic is reported to be flowing in one lane again on State Highway 29 in the lower Kaimai range following a crash earlier.

Police say that they received a report at 3pm that a car had collided with a campervan on SH 29, between McLaren Falls Road and Ngamuwahine Road.

"The campervan was reported to be on its side," says a Police spokesperson.

"Fortunately all those involved only appear to have minor injuries. As of a few minutes ago, traffic was reported to be flowing in one lane."

"The southbound traffic is backed up nearly to the power station," says a SunLive reader.

NZTA advise that due to the crash which is blocking lanes, stop/go traffic management is operating.

"Expect delays in the area and pass the scene with care," says an NZTA spokesperson.

Earlier, 3.25pm: There has been a serious crash on State Highway 29, Lower Kaimai range and traffic is now at a standstill in both directions.

NZTA report that there has been a serious crash near McLaren Falls on SH29.

It is unknown at this stage whether there are any injuries.

"Delays are likely," says an NZTA spokesperson.

A Sunlive motorist has reported that traffic is at a standstill.

"Traffic has stopped in both directions, and has done for about 20 minutes,' says the SunLive reader.

"Police are in attendance. Traffic will be building back right up to Tauriko and up the Kaimais both ways.

"We are back from the Kaimai School, about a kilometre away from it. Everyone has their cars turned off and are stuck in traffic.

"We encourage everyone to avoid travelling for a while."

An update will be provided once more information comes to hand.

At the scene? Phone 0800 SUNLIVE or email newsroom@thesun.co.nz