KABUL, Afghanistan (CNN) -- Fifteen students were among the 25 people killed when a truck rigged with explosives detonated south of Afghanistan's capital, local officials said.
At first, officials thought the attack near Kabul had targeted NATO troops, but later that appeared not to be the case, said Zamarai Bashari, spokesman for the Interior Ministry.
The incident took place in Logar province.
Twenty-one civilians and four policemen were killed in the attack, said Bashari.
Ten other people were wounded in the attack. Many of the wounded were students going to school, the Interior Ministry spokesman said.
Taliban officials denied responsibility for the bombing on local radio.
In southern Afghanistan, two NATO-led soldiers were killed Wednesday in a roadside bombing, NATO's International Security Assistance Force said Thursday. The nationalities were not disclosed.
Also, the U.S. military confirmed that two U.S. Marines were killed in Helmand province Wednesday. The Marines are leading a major operation against the Taliban in that province.