UPDATED: Both lanes of State Highway 2 are completely open following a truck and car crash this morning.

The southbound lane was blocked just before 7am, after a car and truck crashed on the highway near Morton Road.

Traffic is backed up on SH2. Photo: Supplied.

Minor injuries have been reported from the crash.

A witness to the accident posted on SunLive's Facebook page that it was pitch black and pouring with rain when the crashed happened.

"I was in the car directly behind the car that crashed into the truck. We had both just overtaken a slow truck at the passing lane heading towards Katikati from Tauranga, but we were both travelling under 100km/h," the post reads.

"Pitch black, pouring rain and we come around a bend to find a large truck across our side of the road. Apparently the truck had driven into the ditch on our side of the road earlier and it was backing out."

Police are investigating a cause of the crash.

Earlier:

A crash involving a truck and car is blocking State Highway 2, near Aongatete, this morning.

Police, fire and St John Paramedics have been called to the scene of the crash, which is at the end of the passing lane, just past Morton Road.

A Northern Fire Communications spokesperson says the truck is in the middle of the road, and both the car and truck blocking one lane.

It's unclear what injuries have been sustained and there are no reports of anyone being trapped.

The car involved in the crash sustained major damage to its front. Photo: Supplied.

People are being asked to expect delays or avoid the area if possible.

Western Bay of Plenty road policing manager Senior Sergeant Ian Campion is asking people to put off travelling today, if they can.

'Not only have we got the rain, but it's compounded also by wind gusts and we already have the weather activated speed limit signs activated on the Kaimai Range."

Ian says conditions are particularly poor over the Kaimai Summit.

'My recommendation to people is if they can put their trip off until the weather improves then that will be the safest option at this stage.

'If it's essential that you travel just make sure you keep your speeds down you respect following distances, put your headlights on to make sure you are visible, and take extreme care.”

The crash is located on SH2, between Work Road and Morton Road. Image: Google Maps.