A suicide bomber blew himself up at a Shi'ite mosque in eastern Saudi Arabia during Friday prayers, residents said, killing about 20 people. No one has immediately claimed responsibility for the bombing but the attack could further harm relations between Sunnis and Shi'ites in the Gulf region. Tensions has been on the rise for weeks as Saudi-led military operations in Yemen fight against Shi'ite Houthi fighters seen as proxies of regional Shi'ite power Iran. In Yemen, a bomb at a Houthi mosque in the capital of Sanna on Friday was claimed by Islamic State.
