A shark killed a woman and seriously wounded a man taking a morning swim together at a national park beach on Australia's east coast Thursday, police said.Experts say a shark rarely attacks more than one person. The attack occurred at Crowdy Bay National Park, which is known for beach camping, fishing spots and hiking 360 kilometers (224 miles) north of Sydney. Police Chief Insp. Timothy Bayly told local media that emergency services were called to the beach after reports that two people in their mid-20s had been bitten by a shark at 6:30 a.m.