A female suicide bomber concealing explosives beneath her black robe struck outside a government complex northeast of Baghdad, killing at least 15 people and wounding more than 40, US and Iraqi officials said.
It was the 21st suicide mission carried out by a woman in Iraq this year, the US military said, as al-Qaida and other Sunni militant groups try to regroup from major losses suffered at the hands of US and Iraqi forces.
The blast occurred about 1 pm on Sunday as dozens of people were leaving a walled compound that includes a courthouse and the provincial governor's office in Baqouba, capital of Diyala province and a former al-Qaida in Iraq stronghold 56 kilometers northeast of Baghdad.
A car bomb across the street from the same compound killed at least 40 people in April.
It appeared that the latest attack was timed to maximize casualties since many people were leaving the compound because the government offices there were to close soon for the day.
A US military statement said the dead included seven Iraqi police and eight civilians. Ten police were among the wounded. Iraqi authorities said 16 people were killed and 42 wounded.
"I was trying to leave the court when the explosion took place," said one witness, who was wounded by shrapnel but refused to give his name because of fears for his own safety.
"I heard some of the injured people saying they saw a woman wearing a black robe blow herself up."
Al-Qaida has been increasingly using women because their black, billowing abaya robes easily conceal explosives.