Robert Burns,?Lynne O’Donnell?and Ken Dilanian

WASHINGTON: The U.S. airstrike that killed 31 civilians at a hospital in Afghanistan last month resulted from preventable errors by soldiers and airmen who violated rules of engagement and have been removed from duty while awaiting further investigation, military officials said Wednesday.

A briefing in Kabul provided the latest U.S. explanation but left some questions unanswered about an attack in which an internationally run hospital was subjected to barrages of heavy fire from an AC-130 gunship. Among them: how the attack was ordered in a populated area based on a ground commander’s request with little apparent review by higher headquarters.

Gen. John Campbell, the top U.S. commander in Afghanistan, said the airstrike was supposed to have been directed at a nearby facility being used as a Taliban command center but the warplane fired at the wrong building.

After the plane’s targeting sensors malfunctioned, he said, the crew relied on a physical description to home in on the target. But no Americans on the ground were in position to see the hospital.

“This was a tragic but avoidable accident caused primarily by human error,” said Campbell, who described the results of parallel investigations to reporters in Afghanistan and listening in at the Pentagon in Washington.

A summary of one of the investigations, obtained by the Associated Press, said that witnesses differed in their versions of how and why the strike was authorized. It also said the Special Forces commander who called in the strike, identified by AP sources as a major, had been given the coordinates of the hospital two days before but said he didn’t recall seeing them.

Investigators found that the air crew continued the attack despite observing no hostile activity from the hospital, operated by the international group Doctors Without Borders. It found no evidence that armed Taliban were operating from there.

Campbell said several people had been removed from duty over the incident as they await potential criminal prosecution or administrative discipline, although he declined to say who and how many. His spokesman, Brig. Gen. Wilson Shoffner, said those who called in and carried out the airstrike violated U.S. rules of engagement and used force that was disproportionate to the threat — language that suggests a possible international law violation.

“The investigating officer’s recommendations on this have been referred to the proper authorities for disposition,” Shoffner said.

Shoffner would not say whether Campbell, who was out of the country during the incident, was interviewed as part of the investigation.

Doctors without Borders director Christopher Stokes said the update “illustrates gross negligence on the part of U.S. forces and violations of the rules of war.” He renewed his group’s call for an independent international investigation, something the U.S. has blocked by declining to consent.