Suicide bomber hits coalition forces' convoy, killing 6 Afghans May 16, 2013 -- Updated 0804 GMT (1604 HKT) Fatalities included two children and an additional 30 people wounded, Insurgent group Hezbe Islami claims responsibility The group's founder is a former prime minister (CNN) -- A suicide car bomber targeted a convoy of coalition forces in the Afghanistan capital on Thursday morning, killing six civilians, the interior ministry said. The fatalities included two children and an additional 30 people wounded, said Sediq Seddiqi, a spokesman for the ministry. Maj. Bryan Woods, a spokesman for the International Security Assistance Force, confirmed the attack. He declined to release the number of casualties, saying he wanted more time. An investigation is under way, both by the coalition forces and the Afghan officials, Woods said. Insurgent group Hezbe Islami of Gulbuddin Hekmatyar claimed responsibility for the attack. "We had planned this for days before we got a chance to target American advisers," said Haroon Zarghon, a spokesman for the group. The group's founder, Gulbuddin Hekmatya, is a former prime minister. Since the fall of the Taliban regime in 2001, he has been against the government and the presence of the foreign forces in Afghanistan. He is not under the Taliban leadership, but operates alongside them.