KUNDUZ (Afghanistan): The top U.S. and NATO commander in Afghanistan is “very seriously” concerned over reports that civilians may have died in an air strike against hijacked fuel tankers, an aide said on Saturday, as the alliance investigated the attack that killed at least 70 people.

A U.S. F-15E Strike Eagle jet dropped two 225-kg bombs on the two tankers early on Friday after they were seized by the Taliban in Kunduz province. Local officials said the ensuing fireball killed both militants and villagers who had swarmed around the tanks to siphon off the fuel, but it was unclear how many were civilians.

The air strike occurred despite General Stanley McChrystal’s orders restricting use of airpower if civilian lives are at risk. High civilian casualties in military operations have enraged Afghans and undercut support for the war against the Taliban.

General McChrystal discussed the incident with Afghan President Hamid Karzai and later told senior commanders that “we need to know what we are hitting,” the aide said, speaking on condition of anonymity under command policy.

A 10-member NATO investigative team flew over the site on the Kunduz river where the U.S. jet, called in by the German military, bombed the tankers, which reportedly had become stuck trying to cross a river. German officials have said the Taliban may have been planning a suicide attack on the military’s nearby Kunduz base using the hijacked tankers.

The investigative team led by U.S. Rear Admiral Gregory J. Smith, NATO’s Director of Communications in Kabul, also spoke to two wounded villagers in the Kunduz hospital. Admiral Smith said it was unclear yet how many civilians were at the site of the blastMohammad Shafi (10), who was injured in the blast and shifted to Kabul for treatment, said his father told him not to go near the tankers, but he went anyway. “While I was going to get the fuel, on the way I heard a big bang, and after that I don’t know what happened,” he said from his hospital bed, with bandages on his arm and leg.

A bomb blast, meanwhile, hit a German military convoy on Saturday, damaging at least one vehicle and wounding four troops, none seriously. Kunduz provincial police chief Abdullah Razaq Yaqoobi said a suicide car bomb caused the blast, though German military officials said it was a roadside bomb.

Germany said 57 fighters were killed in Friday’s air strike and no civilians were believed in the area at the time, based on surveillance of the tankers by a drone aircraft. NATO Secretary-General Anders Fogh Rasmussen, however, acknowledged some civilians may have died, and the U.S.-led coalition and the Afghan government announced a joint investigation. — AP