A third patient who was injured is not being transferred to hospital, the spokeswoman said.
A Fire Service spokesman said the two-car crash was near the Fanshawe St off-ramp, and emergency personnel were working to free one person who is trapped.
According to NZ Transport Agency, the State Highway 1 link to SH16 towards the Ports of Auckland and westbound was closed, and motorists were advised to avoid the area or delay trips if possible.
In a statement, NZTA said motorists wanting to access the Northwestern Motorway should take State Highway 18 or exit at Fanshawe St.
delays southbound on Northern Motorway2:00PM FINAL UPDATE
All lanes southbound through St Mary's Bay and onto the Southern Mwy, the Northwestern Mwy and to Cook St and Port are NOW OPEN again with traffic now flowing normally in the area.
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1:40PM UPDATE
The breakdown on the Akld Harbour Bridge is now clear, however southbound lanes to Port/SH16 remain blocked as below.
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1:10PM UPDATE
Southbound lanes to Port/SH16 remain blocked as below - however a breakdown is now also blocking the far right southbound lane on the Akld Harbour Bridge. Please pass with care.
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12:50PM UPDATE
All lanes are now open on the Northern Motorway link to the Southern Motorway.
The Northern Motorway link to Port/State Highway 16 is still completely blocked.
If you're heading to the North Western Motorway take SH18, or come off at Fanshawe St. ^LC
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12:15PM 3 APR - LANES BLOCKED - NORTHERN MOTORWAY
A crash is blocking all lanes southbound on the Northern Motorway link to Port/State Highway 16, and the left lane on the link to the Southern Motorway.
Motorists are advised to avoid the area and expect long delays heading south. If you're heading to the North Western Motorway take SH18, or come off at Fanshawe St.
Check our website for travel times, congestion mapping, and web cameras: www.nzta.govt.nz/traffic ^LC
Posted by Waka Kotahi NZ Transport Agency - Auckland on Sunday, 2 April 2017
More to come.