Four whales from a larger pod have died after stranding themselves on Uretiti Beach near Ruakaka, south of Whangārei, this morning.
They appear to be pilot whales - a cetacean species well-known to strand.
More whales have been seen milling close offshore, Project Jonah New Zealand said on Facebook, and there is concern they could also beach.
Project Jonah confirmed about 8.30am that all four whales on shore had died, while the rest of the pod could be seen heading south, towards Lang's Beach.
Project Jonah has sent their volunteer Northland medics to Ruakaka to monitor the situation, with a rescue trailer and senior team on the way.
The Department of Conservation was also on site.
Project Jonah asked people to not head to the beach at this time.