Iraqi police say a female suicide bomber has killed four people and wounded 12 others, northeast of Baghdad.

Police say the woman detonated her explosives-packed vest Wednesday near a police patrol in Balad Ruz in volatile Diyala province. At least one police officer was killed and three were wounded in the attack, which came five years after the start of the Iraq war.

The attack was the latest suicide bombing carried out by a woman.

Early last month, two mentally disabled women strapped with explosives set off by remote control killed 99 people in twin suicide bombings in Baghdad. The U.S military said al-Qaida in Iraq was responsible for those bombings.

In other violence today, the U.S. military says its troops accidentally killed at least three policemen and wounded another in an attack in the northern Iraqi province of Kurkuk.

In other news, Iraqi political leaders ended a two-day unity conference Wednesday by condemning terrorism. Iraq's main Sunni Muslim bloc boycotted the conference and a Shi'ite party loyal to anti-U.S. cleric Moqtada al-Sadr walked out of the event after it began.

Some information for this report was provided by AP and Reuters.