Task Force Lightning
The US army's Task Force Lightning is based in Tikrit, the former hometown of executed Iraqi dictator Saddam Hussein, and patrols a wide area of northern Iraq rife with Sunni armed groups.
The deaths brought to 3,182 the US military's losses in Iraq since the March 2003 invasion, according to an AFP tally based on Pentagon figures.
Iraqi and US forces are in the third week of a security crackdown in Baghdad aimed at stemming sectarian violence.
US military commanders had expressed concerns that fighters could step up attacks outside Baghdad while the operation was under way in the capital.