Gunmen have shot dead eight workers at Iraq's largest oil refinery in the northern town of Baiji, 180km (110 miles) north of Baghdad, police say.
Another man was wounded when the gunmen ambushed the workers' minibus at a roadblock as it drove out of the refinery.
Baiji is a Sunni Arab city which has become rife with insurgent activity.
In December, the security threat forced officials to close the refinery, which processes 200,000 barrels of oil a day.
In other violence on Thursday, a woman lawyer was shot dead as she got out of a taxi in the southern city of Basra.
A US airman from the 447th Air Expeditionary Group was killed and another wounded when two roadside bombs exploded near Baghdad, the US military said.