Steve Irwin, host of the Animal Planet series The Crocodile Hunter,
was killed Monday during a diving expedition off the coast of Australia, the country's Queensland Police Service confirms.
Irwin, 44, was stung by a stingray while filming a documentary at Batt Reef, Low Isle off Port Douglas at about 11:00 a.m. According to a police statement, "his crew called for medical treatment and the Emergency Management Queensland Helicopter responded; however, Mr. Irwin had died."
Stingrays have poisonous barbs on their tails. John Stainton, who was on board Irwin's boat at the time, told the Associated Press that Irwin "came on top of the stingray and the stingray's barb went up and into his chest and put a hole into his heart."
Stainton said Irwin had been filming a segment for a series called Ocean's Deadliest.
Irwin leaves behind his American-born wife Terri, 42, daughter Bindi, 8, and son Bob, 2.
A tireless wildlife advocate, Irwin's career was not without controversy: In July 2004 he was cleared
of charges that he got too close to penguins, a seal and humpback whales in Antarctica while making a documentary, and in January of that year enraged child welfare groups by holding son Bob
, then 1 month old, while feeding a crocodile.
In 1992, the year The Crocodile Hunter
first began airing, Terri Irwin told PEOPLE of her husband, "The thing that attracts me to him is that passion he has for what he does. The animals have no capacity to return Steve's affection. In fact, all they want to do is kill him."
Irwin himself admitted, "I realize that one mistake and I could be dead, but I've had a lot of experience and mostly I know when there's danger."