A parked car bomb exploded in a residential district of Kirkuk on Saturday, killing four people and injuring another 13, police said. The US command said three US Marines died in action in western Iraq. The bombing occurred around 2 p.m. in the al-Wasiti district of Kirkuk, about 290 kilometers north of Baghdad. It was the sixth car bombing this month in Kirkuk, where tensions are rising among Arabs, Kurds and Turkomen for control of the area's vast oil wealth. Also Saturday, the western regional commander of the Iraqi Border Protection Force, Brig. Gen. Jawad Hadi al-Selawi, was killed in Karbala, 80 kilometers south of Baghdad, police said.