A passerby who stopped at the scene could be seen using power tools from his vehicle to help extricate people trapped in the vehicles involved in the crash.

Police confirmed the South Auckland crash was reported to them about 1.47pm today.

Early indications suggest multiple people have received critical injuries, police said.

St John Ambulance said it was sending 10 vehicles to the accident. A helicopter was also flying to the crash scene.

Posts to social media show a truck, van and at least two other cars with major damage and people walking over the motorway.

According to Google Maps, traffic is backed up for nearly 5kms.

The motorway has been closed in both directions and diversions are in place.

“Motorists heading south will be diverted at Ararimu Road, Ramarama and northbound motorists will be diverted at Mill Road, Bombay,” NZ Police media said.

The Serious Crash Unit has been advised.

NZ Transport Agency has also confirmed all northbound lanes on State Highway 1 between Bombay and Ramarama are currently closed due to a significant crash.

“The right southbound lane is also blocked and people are asked to pass with extra care and expect delays. A full southbound closure may also be necessary so motorists are asked to follow directions of response crews at the scene,” NZ Transport Agency said.

“NZ Transport Agency Waka Kotahi recommends that people delay their travel if possible, avoid the area and use another route.”

MORE TO COME