Seven people were killed and another person was missing after a chartered fishing boat disappeared from view in large waves at the entrance to a harbor near Auckland, New Zealand authorities said.

The boat Francie was carrying 11 people when it got into trouble on Saturday afternoon in Kaipara Harbour. Rescuers managed to pull three survivors from the water, who were taken to a hospital. A search for the missing person was continuing Sunday, said police Inspector Duncan Hall.

Crew members from the boat notified the coast guard that they were attempting to cross a sandbar at the entrance to the harbor at about 2 p.m., said Patrick Holmes, the chief executive of Coastguard New Zealand.

He said the coast guard raised the alarm an hour later after the boat didn't report back and could no longer be reached on its marine radio or by mobile phone.

Other boats in the area reported to the coast guard that they could no longer see the boat, although he wasn't yet clear if it had sunk. An investigation was underway.

Waves at the sandbar were about four meters (13 feet) high at the time of the accident, Holmes said. Sandbars are formed by sand building up on the seafloor, something which can happen at harbor entrances where the ocean meets calmer harbor water.

"All sandbar crossings are dangerous. They shift with storms and tides, so the bars are not in exactly the same position," Holmes said. "Because it's a disturbance of the seafloor, the action of the waves becomes distorted and irregular."

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Eyewitnesses told Television New Zealand that rescuers in helicopters plucked the survivors from the water and placed them on a beach, where locals kept them warm until ambulances arrived.

Police said they were still trying to establish what happened to the boat and how its occupants ended up in the harbor, which is about 75 kilometers (47 miles) northwest of Auckland.

Inspector Hall said rescuers recovered five bodies from the water soon after the accident. Another two bodies washed ashore at nearby beaches and were found early Sunday.

The Facebook page for Francie Charters says its boat Francie is licensed to carry up to 20 people with two crew members. It shows customers using fishing rods to catch snapper and other fish, and encountering dolphins.