Steve Irwin, the hugely popular Australian television personality and conservationist known as the "Crocodile Hunter," was killed Monday by a stingray while filming off the Great Barrier Reef. He was 44.

Irwin was at Batt Reef, off the remote coast of northeastern Queensland state, shooting a segment for a series called "Ocean's Deadliest" when he swam too close to one of the animals, which have a poisonous bard on their tails, his friend and colleague John Stainton said.

"He came on top of the stingray and the stingray's barb went up and into his chest and put a hole into his heart," said Stainton, who was on board Irwin's boat at the time.

Crew members aboard the boat, Croc One, called emergency services in the nearest city, Cairns, and administered CPR as they rushed the boat to nearby Low Isle to meet a rescue helicopter. Medical staff pronounced Irwin dead when they arrived a short time later, Stainton said.

Just week ago, the City of Los Angeles retained Irwin to help capture Reggie, the elusive alligator who has been living in Machado Lake.

"I never thought Reggie was going to be an easy catch," Irwin said. "He has all the food he needs -- fresh fish and birds ... 53 acres of water to hunt and hide ... topped off with some gorgeous L.A. weather ... What more could a young gator want? ... I will certainly try to do whatever I can to help the City of L.A. come to a safe and happy conclusion to the Reggie saga."

Irwin said he would be on a plane from Australia the next time Reggie was spotted.