CAIRNS, Australia - Steve Irwin, the hugely popular Australian television personality and environmentalist known as the "Crocodile Hunter," was killed Monday by a stingray during a diving expedition. He was 44.

Irwin was filming an underwater documentary on the Great Barrier Reef in northeastern Queensland state when he was stung, Sydney's The Daily Telegraph newspaper reported on its Web site.

He collapsed at Batt Reef, near Low Isle and the resort town of Port Douglas, Queensland state police said in a statement. Port Douglas is about 1,260 miles north of Brisbane, the state capital.

A rescue helicopter rushed to the scene but Irwin had died, the statement said.

Queensland ambulance service spokesman Bob Hamil confirmed that a diver had been killed by a stingray off Lowe Isles Reef and said cause of death appeared to be a "stingray strike to the chest."

Irwin was famous for his enthusiasm for wildlife and his catchword "Crikey!" in his television program "Crocodile Hunter," which was first broadcast in Australia in 1992 and has aired around the world on the Discovery channel.

He rode his image into a feature film, and developed the Australia Zoo as a tourist attraction.

“The world has lost a great wildlife icon, a passionate conservationist and one of the proudest dads on the planet,” John Stainton, Irwin’s friend and producer, said in the statement. “He died doing what he loves best and left this world in a happy and peaceful state of mind. Crocs Rule!”