MOSUL, Iraq, Oct. 28 (Xinhua) -- Unknown gunmen on Tuesday shot dead four people and wounded four others at a police recruiting center in the volatile city of Mosul, capital of Nineveh province, a provincial police source said.

    The attackers opened small-arms fire on many recruits when they were lining up outside the center to join Iraqi police in the Hay al-Amil neighborhood in southern Mosul, the source told Xinhua on condition of anonymity.

    The attack resulted in the killing of four recruits and the wounding of four others, the source said.

    Iraqi security forces immediately blocked the crowded street and searched the surrounding area for the attackers, he said, adding ambulances rushed there and evacuated the casualties to nearby hospitals.

    Nineveh province, together with its capital Mosul, some 400 km north of Baghdad, is said to be one of the last strongholds of al-Qaida fighters in the war-torn country.

    The province has been the scene of a major security crackdown by U.S. troops and Iraqi security forces, which was aimed at uprooting al-Qaida militants and other anti-U.S. insurgent groups.