Afghanistan ? A suicide bomber rammed his explosives-laden car into a minibus full of Afghan soldiers south of Kabul today, killing at least 13 people and wounding 20, officials and witnesses said.

The Taliban claimed responsibility for the attack, which happened on the last morning of Defense Secretary Robert Gates’ two-day visit to Afghanistan. It was not immediately clear whether Gates was still in the country at the time.

Gen. Mohammad Zahir Azimi, a defense ministry spokesman, said six soldiers and seven civilians were killed in the attack. Four of the civilians were children, said Abdullah Fahim, a health ministry spokesman.

The blast was the third suicide attack in the capital in the last eight days. It follows a similar attack against a NATO convoy on Tuesday that left 22 civilians wounded.