WASHINGTON -- The pilot of an American F-16 fighter jet thought he was under attack from ground fire when he dropped a 500-pound laser-guided bomb on a group of Canadian soldiers conducting a live-fire exercise in Afghanistan, killing four soldiers and wounding eight, Pentagon officials said Thursday.
"He reported being under fire from the ground," said a senior defense official, speaking on condition of anonymity.
The jet was one of two Air National Guard F-16s that were on patrol over a training area at a former al Qaida base known as Turnak Farms, just south of the American-led coalition base at Kandahar airport when the incident occurred about 1:55 a.m. Thursday local Afghan time.
One of the pilots, apparently spotting tracer fire from the Canadian exercise on the ground below, radioed in that they were taking fire and released the bomb, officials said. It remains unclear if the pilot received permission to bomb, one official said. Normally, a pilot must receive clearance, but would not need permission if he felt in immediate danger. "In an instance like this of self-defense, he has the right to drop on his own authority," the official said.
Among the wounded, two suffered life-threatening injuries but were in stable condition, Canadian officials said.
About 100 members of the 3rd Battalion, Princess Patricia's Canadian Light Infantry Battle Group were conducting fire and maneuver exercises on foot when the bomb struck. No American forces were involved in the exercise.
The 800-man battle group has been in Afghanistan since late January. The battalion had been used during the second half of Operation Anaconda to flush Taliban and al Qaida guerrillas out of the Shah-e-Kot mountains, said Maj. Bryan Hilferty, a U.S. military spokesman at Bagram air base, near Kabul.
Defense Secretary Donald H. Rumsfeld promised an investigation. Canadian Defense Minister Arthur Eggleton said in Ottawa that Canada would form its own board of inquiry, but that both sides had agreed to conduct a joint investigation.
Gen. Raymond Henault, chief of the Canadian Defense Staff, said the area was frequently used for live-fire exercises by all coalition forces, and that the Canadian exercise had taken place with proper coordination with the American chain of command at Kandahar airfield. Both officials said the investigation would review all aspects of the incident, including communication between ground and air forces.
"Whether or not the pilot had the authorization to drop or not is something that will come out in the fullness of the investigation," Henault said. "But I do remind you that any pilot, any individual who's operating in that theater of operations, whether land force member or air crew member, has the right of self-defense, and that is what always overrides anything else in this circumstance, which is a combat operation."
A second Pentagon official, also speaking on condition of anonymity, cautioned that the investigation was in preliminary stages and that information was sketchy.
A total of 41 American and coalition soldiers have died in Afghanistan or the surrounding region since the war began six months ago, according to U.S. Central Command, which has responsibility for running the war. Seven of them have died in "friendly fire" incidents, including the four Canadians.
On Dec. 5, three Americans and nine Afghans were killed, and more than three dozen others were wounded when an American B-52 accidentally bombed a Special Forces team supporting anti-Taliban fighters north of Kandahar.
The deaths Thursday were the first Canadian casualties in the war and the country's first combat deaths since the 1950-1953 Korean War.
Michael Zielenziger in Kabul, Afghanistan, contributed to this report.