An explosion near a two-vehicle convoy killed three German nationals Wednesday on the outskirts of the Afghan capital, police officials said. Kabul deputy police chief Zalmay Khan said three German soldiers were killed in the blast, but the German Defense ministry denied that the victims were soldiers. The explosion near the convoy, which was traveling on an unpaved road about 10 kilometers southeast of Kabul, turned one of the two vehicles onto its side and left it badly damaged. NATO's International Security Assistance Force said it was aware of an explosion near a military base but didn't know how many casualties there were. The force said it believed the blast was caused by a land mine. Amir Mohammad, a police officer, said it was not clear if the mine was recently planted or an old one. After the explosion, two helicopters arrived at the scene. One took the bodies away, said Mohammad Sharif, a witness who has a shop near the area. Later, French troops with anti-mine equipment and US troops arrived at the scene. Afghan police kept reporters from getting close to the site, as forensic experts collected evidence. Afghanistan has suffered nearly three decades of civil war and conflict, and is one of the most heavily mined countries in the world. Separately, US-led coalition and Afghan troops clashed with militants in central Logar province on Tuesday, killing nine suspected militants, the Interior Ministry said. No police or coalition troops were wounded in the clash, it said.