A man has been killed by a shark believed to be up to 14ft long.

Adam Strange, who was in his 40s, was swimming off New Zealand's Muriwai beach near Auckland when the shark attacked.

His family said that Strange was a ''glorious and great father, husband and friend''. He was a well-known filmmaker who had been a finalist at the Cannes International Advertising Awards.

In his spare time, Strange said he liked to surf on the West Coast. He also enjoyed skiing, mountain biking and live music.

Pio Mose, a witness who was fishing from the beach, told the New Zealand Herald that he saw the swimmer struggling against the shark, which he described as "huge". Mose told Strange to try to swim to nearby rocks.

"All of a sudden there was blood everywhere. I was shaking, scared, panicked. The water was red."

He said other sharks began approaching after the attack. He watched the shark drag Strange's body further out to sea.

Shot at 20 times

"All I was thinking was I wanted to jump in the water and help but I didn't want to get attacked by a shark too," Mose said.

The beach has been closed since the attack and.

Police inspector Shawn Rutene said the swimmer had been around 200 metres from shore. Rescue crews took an inflatable boat out and shot at the shark 20 times but it vanished below the surface.

"It rolled over and disappeared," Rutene said.

Muriwai Surf Lifeguard chairman Tim Jago said three lifeguards aided the police and that they had known Strange. Jago described the death as traumatising.

Two hundred people were on the beach when the shark attacked. Experts believe it was a great white.

Clinton Duffy, a shark expert with the Department of Conservation, said the waters around New Zealand are home to a large number of great whites, but they also harbour several other potentially lethal species.