BAGHDAD - Mortar rounds hit an Iraqi Sunni Muslim mosque and a bomb exploded in a Shi'ite mosque on Friday in attacks that killed eight and fueled tensions a day before provincial elections.Troops also fired on Sunni Muslim protesters in Kirkuk in clashes that killed at least two people during a rally against Shi'ite Prime Minister Nuri al-Maliki.Saturday's ballot will test Iraq's political stability, with Maliki's fragile government already caught up in a crisis over power-sharing among Shi'ite, Sunni and ethnic Kurds more than a year after the last US troops left.