The US army says it has killed more than 500 insurgents since the battle of Falluja began on Monday. Fierce combat continues in the rebel stronghold. American and Iraqi troops have punched through the Jolan district of the city, reportedly encountering little resistance. Coalition forces now say they have around 70 percent of Falluja under their control.Insurgents have attacked elsewhere in response to the offensive. In the northern city of Mosul, militants set police stations ablaze, stole weapons and roamed the streets. There has also been unrest in Ramadi, Baquba, and Tikrit. In scenes which have become all too familiar in Baghdad, at least 17 people were killed and more than 20 were injured in a car bomb attack. The blast happened in a busy commercial thoroughfare.