Eight family members were killed Wednesday in a gunfire attack on their house in northern Iraq, a provincial police source said.

The predawn attack occurred when gunmen stormed the house of Adnan Khayrallah, a prosecutor in the city of Baiji, some 200 km north of Baghdad, a provincial police source told Xinhua on condition of anonymity.

The attackers shot dead Adana, his father, three women, two children along with a guest, the source said without giving further details.

On July 22, al-Qaida in Iraq announced in a new plan to free the group's jailed members and to assault the country's judges and investigators.

Violence is still common in the Iraqi cities despite the dramatic decrease since its peak in 2006 and 2007, when the country was engulfed in sectarian killings.