A two-car crash is causing heavy congestion on State Highway 1 south of Warkworth.
A fire service spokesman said one person was injured, but not trapped.
The crash occurred between Woodcocks and Toovey Rds.
A woman who drove past the scene said there were several ambulances and police cars attending the incident.
Firefighters were directing traffic, which she said was heavy in both directions.
The NZTA has advised motorists to expect delays.