STUART, Fla. -- Sharks killed a man kite surfing off South Florida's Atlantic coast in the state's first deadly shark attack in five years, authorities said.

A lifeguard spotted Stephen Howard Schafer, 38, in distress Wednesday about 500 yards off the beach near Stuart. When he paddled out, he found Schafer bleeding and surrounded by several sharks. Schafer was taken to a hospital and died a short time later, according to Rhonda Irons, public information officer for the Martin County Sheriff's Office.

Authorities are investigating what types of sharks may have been involved.

Meanwhile, beaches remained open in the area Thursday.

Shark attacks, especially fatal ones, are extremely rare, said George Burgess, a leading shark expert who directs the International Shark Attack File at the University of Florida's Museum of Natural History.

The attack on Schafer was the 14th deadly one in the state since 1896.

``Internationally, we've been averaging four fatalities per year, despite the fact that there are billions and billions of human hours spent in the sea every year,'' Burgess said Thursday. ``Your chances of dying in the mouth of a shark are close to infinitesimal.''

The United States leads the world in the number of unprovoked shark attacks, some deadly, some not, with about 1,032 documented since 1670, according to the International Shark Attack File. Of those, 50 were fatal. Florida leads the world with more than 600 attacks.

The last fatal shark attack in the state was in 2005 off the Florida Panhandle, where a 14-year-old Louisiana girl was attacked while swimming on a boogie board about 100 yards off shore.

``Florida as a geographic entity has more [shark attacks] than any other place in the world,'' Burgess said, noting that most attacks are minor, ``the equivalent of a dog bite.''

While attacks are rare, Burgess said, people still need to be careful in the ocean.

``We need to respect it. When we enter the sea, there are certain risks that we should expect,'' he said.

However, Burgess noted that this time of year there are typically fewer shark attacks in Florida because temperatures are cooler and not as many people are in the water.

He said sharks are lining ``up in South Florida getting ready to move north'' as temperatures begin to warm.

``The sharks gradually move their way northward and disperse,'' Burgess said. ``The message to take home is this is a rare and unusual event. It should put the antennae up for people, in terms of, `Yeah, we need to be careful when we enter the sea,' but we need to do that every time because we're never guaranteed safety 100 percent of the time when we enter a wild world.'''

Billy C.'s POV:

This is a tragically rare event for Great Whites to attack and kill a person in the waters off of Florida. My heart goes out to the family of Mr. Schafer who was enjoying his passion for kitesurfing and the ocean. 

We also need to keep in mind that this was an accident and a case of mistaken identity by the sharks. It is not an indictment on them or their behavior towards humans. I myself have a shark dive planned next week off of Jupiter, Fl. Not that far from where this occurred, I will be filming these amazing animals as they congregate off the coast for their annual mating season. We will be filming Lemon Sharks. The news has captured images of the annual migration of Lemons, Hammerheads, and Bulls as they make their way up and down the Florida coast. Whites? Not so much, we don't know if it was 100% whites that killed Mr. Schafer, could be? Waters off Florida are definitely chillier than normal from our January cold snap. Just look at the photos in my gallery of the fish kill in Florida Bay. 

But the bottom line here is this: this tragic event should not demonize these amazing creatures. This horrible accident was a case of mistaken identity. Sharks react and ask questions later. Murky water is usually the case when shark attacks occur off of our coast. These sharks were just bigger than usual and packed a bigger bite when they swam in these murky waters. In a case like this there is no good news. A family has endured a sudden and devastating loss and sharks are to blame. But keep in mind that they are not a villain.