A suicide bomber wearing an army uniform walked into a crowded mess hall in Khalis, about 45 miles north of Baghdad, and blew himself up as soldiers were gathering for lunch, according to Iraqi army Col. Saleh al-Obeidi.
In another attack, eight Iraqi policemen were killed when a suicide bomber slammed into two police cars in Baghdad. Thirteen bystanders were injured when the cars burst into flames at the scene.
Meanwhile, Iraqi and U.S. troops found and released hostage Douglas Wood, 64, who had been held for 47 days in Baghdad.
Wood, an Australian engineer from Alamo, Calif., said he was "extremely happy and relieved to be free again," according to a message read by Australia's counterterrorism chief Nick Warner, the Associated Press reported.
The raid took place as part of Operation Lightning that began in Baghdad at the end of May. There "was specific intelligence and tips that provided a hint at what might be found at that location," said Warner.
Wood was found under a blanket and the insurgents told troops he was their sick father, said Gen. Naseer al-Abadi, Iraq's deputy chief of staff. The operation also resulted in the arrest of three insurgents and release of an Iraqi hostage, according to the AP.
A militant group calling itself the Shura Council of the Mujahedeen of Iraq abducted Wood and demanded the Australian government withdraw its 1,400 troops from Iraq.
The government refused to accede to the demand and instead sent diplomats, police and military personnel to Baghdad to seek his release.
"I am delighted to inform the House that the Australian hostage in Iraq, Mr. Douglas Wood, is safe," Prime Minister John Howard told Parliament in Canberra, Australia.