Police have named the victim who died in the shark attack at Waihī Beach as 19-year-old Kaelah Marlow.
It is understood she was dragged from the water alive after the attack and paramedics administered CPR on the beach to no avail.
"Police extend our deepest sympathies to Kaelah's family and loved ones at this very difficult time," police said in a statement.
"As noted in an earlier release, the matter will be referred to the Coroner."
Marlow's post mortem is being carried out today.
The attack took place at Bowentown Beach just after 5pm on Thursday and emergency services flooded the area soon afterwards.
The lifeguards who spotted Marlow were patrolling outside of the flags when they spotted her, Surf Lifesaving New Zealand's eastern region lifesaving manager Chaz Gibbons-Campbell says.
Matt Lawry says he looked-on as they worked to save Marlow and says a man was being comforted by an emergency services member nearby.
"Watching them try to save the young woman without success and seeing the man's white face was a very traumatic, harrowing experience," he said.
After CPR efforts stopped, a man walked about 50 to 70 metres into the sea and began splashing water over himself.
"It was harrowing and I can't stop thinking about the extreme grief I saw on his face as he left the beach," Lawry said.
Tadhg Stopford also saw the man walk into the ocean and says he waited in the deep for several minutes standing there.
"His entry into the sea was a challenge, I guess, to the shark who had stolen the life of his loved one … With my children around me, I felt his loss."
Earlier today, iwi from Otawhiwhi Marae installed a rāhui in the area which finishes on Friday next week, banning the collection of shellfish, all fishing, and swimming at the beach.
While the rāhui will remain in place, swimming will be permitted between the flags in certain areas of the beach from tomorrow.
The decision to open areas of the water was made by local kaumātua (elders), Waihi Beach Surf Club officials, Bay of Plenty Harbourmaster manager Jon Jon Peters, and Surf Lifesaving NZ and Western Bay of Plenty District Council representatives.
Signage will be erected to assist the public as to where they can swim.
Gibbons-Campbell said lifeguards from Mount Maunganui and Pukehina Beach would also be assisting to patrol along the beach over the weekend and into next week.
And some of the extra lifeguard resources would be devoted to Anzac Bay to assist anyone concerned about swimming at Bowentown, he said.
Iwi also blessed the area with a karakia and for the compassion and care they showed for the victim and her friends.
Shark scientist Riley Elliott says it's hard to speculate what species of shark attacked the woman without all of the facts at hand.
There has been evidence of juvenile and immature great whites in the area as of last summer, however.