(CNN) -- By the time police officers reached the swimmer floating off a New Zealand beach, it was already too late: a large shark was biting the lifeless body.
The attack took place off a popular beach west of Auckland on Wednesday afternoon, police said, as people gathered there to enjoy the summer sunshine.
The victim was a man in his 40s. He was swimming 200 meters (220 yards) offshore near Muriwai Beach, about 25 kilometers (15 miles) from central Auckland when the 12-to-14-foot shark struck.
"We saw him rolling around, there was blood everywhere on the water," Pio Mose, who was fishing nearby, told local broadcaster 3 News. Mose said he believed at least two other sharks had joined in the frenzy around the body after a few minutes.
The shark that attacked the swimmer was a great white, according to Russell Clark, a paramedic from the Westpac Rescue Helicopter service, which responded to the emergency at the beach.
Police officers and life guards on the scene went out in inflatable boats. When they fired at the shark they saw by the body, it "rolled over and disappeared," said Inspector Shawn Rutene.
Following the death, police closed the beach and several others nearby. Auckland Council said it expected the area to remain closed for the next few days.
Shark attacks kill about 25 people a year worldwide, according to the New Zealand Department of Conservation. However, fatal attacks in the country's beaches have been rare.
There have been fewer than 20 shark attack deaths in more than 175 years in New Zealand, the agency said.
Twitter users expressed their condolences to the victim's family. Others worried about the risk of more attacks.
"Shark attack at Muriwai!!" exclaimed a user named Aaron Jeavons. "Won't be swimming there again!"