Police say a crash which blocked Auckland’s Southwestern Motorway near the airport for more than two hours came after they responded to an earlier incident in Māngere reportedly involving a firearm.

Inspector Jason Homan said the police helicopter Eagle helped observe a vehicle of interest during this afternoon’s incident.

“Around midday police units on the ground signalled the vehicle to stop near George Bolt Memorial Drive. The vehicle has subsequently failed to stop and accelerated away from police.”

He said in the process of doing so the vehicle attempted to pass traffic and collided with two vehicles on an overpass on State Highway 20, south of the Coronation Rd off-ramp.

 “As a result, two members of the public have sustained moderate injuries. The driver who failed to stop has also suffered moderate injuries.”

Homan said all three people have been taken to hospital. There were no reports of injuries in relation to the initial incident.

“The Serious Crash Unit is attending the incident and an investigation is underway into the original incident and the crash. As is standard procedure in these circumstances, police will also be notifying the Independent Police Conduct Authority.”

Motorists are being asked to delay their journey or exit the motorway at SH20A or Massey Rd.

One eyewitness told Newstalk ZB cars were flipped in the crash.

A police spokesperson said the crash, involving two vehicles, was reported to authorities about 12.30pm.

The crashes caused gridlock on State Highway 20. Photo / File