A string of powerful bomb attacks targeting Shiite Muslim worshippers as they emerged from mosques across Baghdad on Friday killed at least 28 people and wounded more than 50, police and hospital officials said. The six apparently coordinated blasts occurred outside mosques and prayer centers in and around the capital, including one frequented by followers of radical Shiite cleric Moqtada Al-Sadr, they said. The most devastating attack was in the northeastern Baghdad district of Al-Shaab, where a car bomb killed 21 people and injured 35 others, an interior ministry official said. The bombings come exactly one month after the US troops pulled out from cities across Iraq, handing over security to Iraqi forces. In twin bombings at Diyala bridge, 10 km south of Baghdad, four people were killed and seven wounded. Attacks in Zafaraniyah and Kamaliyah neighborhoods killed one person each and left six and three people wounded respectively. A separate attack in Al-Elam in western Baghdad injured four. Attacks in Baghdad over the past two months have mostly targetted Iraq's majority Shiite community, prompting fears of efforts by Al-Qaeda fighters to reignite the sectarian violence that swept the country, killing tens of thousands of people, in 2006 and 2007. On Wednesday a senior US commander warned that security forces would have to be watchful of violence targeting parties and politicians in the run-up to general elections next January. “Leading up to the elections, we're also going to see some politically-motivated violence,” said Colonel Tobin Green, commander of the US army's 1st Brigade, 1st Cavalry Division.