in the Sadr City area of Baghdad, killing at least 13 people and wounding 30 more. Elsewhere four Iraqi civilians died in a suicide bombing of an American base in Tikrit, Saddam Hussein's home town, and four American soldiers were killed by rockets at their base in Taji near the capital. American officials also said that five Iraqis had been killed in a gun battle in the central shrine city of Kerbala, the stronghold of firebrand cleric Muqtada al-Sadr, after they attacked a coalition base early on Saturday and an American infantryman was killed by a roadside bomb. Three mortars hit the market in Sadr City, a poverty-stricken Shia area that is largely controlled by extremist cleric Muqtada al-Sadr, at around 11am. Al Sadr has led a rebellion against the US-led coalition authorities who have sworn to kill or capture him. Local people have been angered by protracted skirmishing between al-Sadr's Mahdi army militia and American troops in recent weeks. Fierce gun battles raged again early on Saturday morning in which at least one civilian was killed and several more injured. Yesterday armed men from this militia, who have established a stronghold in the district's narrow streets, manned checkpoints preventing access to the site of the mortar attack. Witnesses described the scene as carnage. 'The market was very crowded. There was a huge bang and I closed my eyes and when I opened them my legs were on fire,' Ayid Hussein Ismael, 30, told The Observer. 'People were running everywhere