Multiple crashes close part of Auckland's northern motorway

Part of Auckland's northern motorway has been closed by two separate crashes.

Police say the crashes occurred on Greenhithe Bridge on Wednesday.

The first crash, involving three vehicles, occurred near the Squadron Drive off-ramp about 7.24am.

The second happened soon after, "a short distance back up the hill".

One person has been moderately injured.

"The motorway has been closed while emergency services clear the scene.

"Police are asking motorists to exercise caution, expect delays and seek an alternative route if possible."