A US military base in Kabul’s been hit by an explosion. The bomb struck Camp Phoenix, a giant air base near the airport in the Afghan capital. The base is run by America, but also used by some NATO forces.Afghan police say a suicide car bomber struck a convoy of civilian vehicles outside the base, wounding three Afghans and causing several foreign casualties. A spokesman for the U.S. and NATO-led forces, confirmed a blast but gave no further details. The area has been sealed off by Western forces. The base has been hit by mortars and rockets in the past. This year has seen the worst level of violence since the war in Afghanistan started eight years ago.