Two dead, two in hospital after boat 'gets into difficulties' in Bluff Harbour

Two people have tragically lost their lives and another two are in hospital after a boat "got into difficulties" in Bluff Harbour on Friday afternoon.

Police say they were notified of a vessel in trouble not long after midday, and immediately launched a rescue mission alongside Coastguard and ambulance staff.

However not everyone on the boat could be saved. Of the four people onboard only two survived, and are now in a stable condition in hospital.

The rescue operation was carried out in the waters between Bluff Port and Tiwai Wharf, police say.

Coastguard NZ said volunteers from both its Bluff and Riverton branches had joined the rescue mission.

"Thanks... for responding so quickly to this incident and supporting other emergency services," a spokesperson said. "Our thoughts are with whānau, friends and all those affected by this tragedy."

Maritime New Zealand has been advised of the tragedy and police are investigating the deaths on behalf of the Coroner.

"Police would like to hear from anyone who saw a small boat in Bluff Harbour today or who has CCTV footage of the harbour as this may be relevant to our enquiries," a spokesperson said.

"Anyone with information is asked to call 105 and quote event number P048675341."