A car-bomb attack on a main thoroughfare in central Baghdad killed four people on Wednesday, including two police officers who had been patrolling the area, Iraqi police said. The bomb went off at around 9:30 am (0630 GMT) on Saadun street, one of the main streets running through the capital, which has seen a string of attacks in recent days, most of them targeting Iraqi security forces. Overall security in Baghdad has improved dramatically over the past year as US and Iraqi forces allied with local Sunni militias have flooded into formerly ungovernable districts. But militants continue to carry out near-daily attacks.