Major Brian Hilferty says the U.S. and Afghan soldiers spotted more than 10 gunmen setting up a mortar on a hill above their position several miles from the Pakistani border and south of the city of Khost.
He says the Americans called in A-10 gunships, which "neutralized" the mortar. Coalition troops then inspected the area but found no bodies.
"Either (the A-10s) had not killed them at all, or they killed somebody or wounded them and people dragged them off," says Hilferty, adding that most of the fighters had weapons and some were observing the U.S. soldiers below.
"They were going to dig the mortar and aim it at our position," explains Hilferty. "The troops later found some equipment but no mortar at the site."
U.S. Special Forces and coalition troops are searching the mountains around Khost for Taliban and al-Qaida fighters, thought to be operating in small groups in Paktia province. A British-led force of 1,000 troops is searching north of Khost in a sweep called Operation Condor.
British military spokesman Col. Ben Curry said British commandos were "finalizing the clearing of their area of operation" and regrouping. He would not say if the operation, now in its seventh day, was coming to a close. On Tuesday, British troops found a weapons cache, including an 82mm mortar, more than 150 shells, and small arms.
Also, a British soldier suffered severe head injuries when his truck was involved in an accident three miles outside Khost. The soldier, who was driving the vehicle, was in serious condition, but his life was not in danger, Curry said. The military was investigating the accident.
On Tuesday, Canada said it would bring home its 800 ground troops from Afghanistan this summer. Defense Minister Art Eggleton said Navy, Air and Special Forces would continue to help with the campaign.
Eggleton said Canada's military resources were stretched by peacekeeping missions and other duties around the world, making it difficult to keep the 800 troops stationed in Kandahar, Afghanistan.
In April, a U.S. plane mistakenly bombed Canadian troops in Afghanistan, killing four soldiers and wounding eight. Eggleton said the decision to withdraw was unrelated to the bombing accident.
U.S. and French soldiers are training a new national army for Afghanistan that coalition forces hope will be able to take over the work of securing borders and protecting the new government from al-Qaida and the Taliban.
Army Gen. Tommy Franks, commander of the U.S. Central Command, said Tuesday he hopes to have the first 2,000 to 3,000 Afghan soldiers trained within six months.
In other war-related developments: