Four people were killed and at least one was wounded when a roadside bomb exploded near their car in the northern Iraqi city of Tikrit 175 km on Sunday (October 8), police said. The blast destroyed several civilian cars and dead bodies could be seen lying on the side of the street. The target of the blast was not known. In the capital Baghdad, a roadside bomb exploded near a police patrol, wounding 19 people, including seven policemen, police said The blast took place in Nasr Square in central Baghdad. "A sound bomb exploded and when police arrived another bomb went off. The bomb is a shell full of explosives. I did not see dead people , I only saw wounded people," said an eyewitness. The latest attacks come as U.S. and Iraqi troops battled Shi'ite militiamen in the southern city of Diwaniya, killing at least 30 militiamen, the U.S. military said. The fighting underlined the chronic insecurity gripping Iraq, where an estimated 100 people die violently every day. Police reported 28 deaths elsewhere in Iraq, including the discovery of the bullet-riddled body of a senior Interior Ministry official in Baghdad. The U.S. military said two soldiers were killed on Saturday, bringing to 26 the number killed in the past eight days. The military said Iraqi troops had arrested the "high-value" target over the deaths of 20 Iraqi soldiers in a battle with Shi'ite militiamen in Diwaniya on Aug. 28. Diwaniya's southern districts are a stronghold for the Mehdi Army militia of Shi'ite cleric Moqtada al-Sadr, whose movement is a key player in Prime Minister Nuri al-Maliki's government of national unity.