Ambulances are rolling in and out at Whakatane Harbour, as boats bring ashore people injured in the White Island eruption

Up to 20 people are thought to have been injured when the Bay of Plenty island erupted just after 2 this afternoon - and one is in a critical condition.

A search and rescue operation is underway, and NZME reporter Katee Shanks is at the harbour where she's seen boats come in with victims.

She says local boaties have been asked for their assistance - and one has come back covered in ash.

Police and Civil Defence are due to give a briefing on the situation in half an hour and you can listen live on Heather Du Plessis Allan Drive.