BAGHDAD, July 12 (Reuters) - Seven guests celebrating the wedding of an Iraqi policeman were killed on Thursday by a suicide bomber in the northern town of Tal Afar, police said.

The bomber tried to force his way into the party and detonated a suicide vest when some of the guests blocked his path, police said.

Four people were wounded in the attack, 420 km (260 miles) northwest of Baghdad. It was not clear how many casualties, if any, were police, or if the bride or groom were among those hurt.

Tal Afar is a restive town of mainly Sunni and Shi'ite Turkmen to the west of Mosul, whose proximity to the Syrian border makes it a natural stopover for foreign Islamist militants crossing into Iraq.

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