Swimmer fends off shark with diving knife as Hawaii officials report second attack in less than a week

For the second time in less than a week, Hawaii officials put up shark warning signs after a shark bit a man Tuesday. The man, a 68-year-old from Waikoloa, was swimming about 400 yards from shore at Anaehoomalu Bay on the Big Island when he was bitten on the lower left torso, Hawaii county police said.

"The swimmer attempted to fend off the shark with a diving knife and the shark released the swimmer," police said in a news release.

The man was taken to an island hospital. He was in stable condition and was to be transported to Oahu for treatment of injuries that were not life-threatening, police said.