Lebanese and Palestinian security officials say a military commander of the Fatah movement has been critically wounded in a bomb explosion in Lebanon's largest Palestinian refugee camp. The officials say Talal Sleim was heading to his office in the Ein el-Hilweh camp when a roadside bomb exploded nearby. They say the 43-year-old Sleim was seriously wounded and rushed to a hospital. A bodyguard was lightly wounded. After news of Tuesday's explosion spread, Fatah guerrillas exchanged machine gun fire with Palestinian gunmen of the Jund al-Sham group, which follows the extremist ideology of al-Qaida. The officials spoke on condition of anonymity because they were not authorized to speak to the media.