Several sharks were involved in a deadly attack on a New Zealand man, a coroner has found.

Adam Strange, 47, from Auckland, was killed in a rare shark attack at Muriwai Beach on Auckland’s west coast in February.

In a ruling on Wednesday, coroner Morag McDowell said the television commercial and film director died of blood loss from multiple shark bites, mostly to his legs, while there was also evidence of drowning.

Mr Strange was swimming in preparation for an upcoming race when the attack happened shortly after 1pm on February 27.

A fisherman noticed Mr Strange was being followed by a lot of birds and there were schools of small fish around him.

Two minutes after spotting the swimmer, the fisherman heard splashing and Mr Strange’s calls for help, and saw a lot of blood in the water.

The fisherman, who was not named, told the inquest he saw more than one shark attacking Mr Strange, who became limp and was face down in the water.

The man called emergency services.

A friend of Mr Strange, who was surfing at Muriwai Beach, also saw the attack, and recalled seeing a number of shark fins.

Surf lifesavers were alerted at 1.30pm and raced to Mr Strange’s aid.

When they reached him, a single shark, measuring about three to four metres, had hold of him.

Lifesavers used their boat and oars to get the shark to release Mr Strange and kept it at bay until police arrived, and shots were fired at the shark, which sank below the water’s surface.

Mr Strange’s body was then recovered.

Surf Lifesaving NZ told the inquest there had not been a recorded shark attack in west Auckland waters for at least 30 years.

Despite the rarity of the attack, the area is a known breeding ground for sharks.