A northern fire communications spokesman said they were called to the scene about 5.51am.
Four vehicles were involved in what is thought to be a minor crash, he said, as no one was trapped and no injuries were reported.
SH20 SOUTHWESTERN MWY, SOUTHBOUND - 6:05AM A crash is blocking the right lane southbound at Hillsborough Rd interchange. Pass with care and expect delays until cleared. ^TP pic.twitter.com/UIexRlAJM3
— Waka Kotahi NZTA Auckland & Northland (@WakaKotahiAkNth) February 20, 2020
A traffic camera image shows long queues snaking down one side of the motorway.
On the other side, a number of vehicles can be seen parked up and a number of people standing on the road. At least one appears to be a firefighter.