Bombs and shootings have killed at least 15 people in Iraq, police said Wednesday.

Two car bombs exploded in quick succession near each other in western Baghdad on Wednesday, killing eight people and wounding 20, a police officer said. He spoke on condition of anonymity because he was not authorized to speak to the media.

In another attack Wednesday in downtown Baghdad, a roadside bomb that exploded at an intersection killed three people and wounded six, police said. Two traffic policemen were among the dead, they added.

In an attack on Tuesday night, gunmen in the northern city of Kirkuk opened fire on a car, killing three civilians and injuring another, said Brig. Sarhad Qadir, the head of Kirkuk police.

Also Tuesday night, a car bomb killed Muhanned Abdul-Jabbar, a senior official with a U.S.-backed group of Sunni fighters in Ramadi, west of Baghdad. It detonated when he left his house after dinner, police said.

Violence has dropped dramatically in Iraq since last year, but insurgents retain the ability to strike and U.S. military officials have warned that the security gains remain fragile.