The paratrooper from the 82nd Airborne Division is in stable condition at a field hospital at Bagram Air Base, just north of Kabul, after being shot on a reconnaissance patrol near Lwara in Paktia province.
"We have no information on the people who conducted the ambush," said Roger King, a U.S. military spokesman at Bagram Air Base. "It was apparently a few shots, and then they moved away. They were not engaged."
Earlier Wednesday, a dozen gunmen were killed in a shootout with Afghan soldiers. The Afghan foreign minister reported Thursday they were Pakistani members of al Qaeda who had escaped from intelligence service detention in Kabul just hours earlier.
Three of the group killed themselves by detonating grenades as soldiers closed in on them Wednesday morning, Foreign Minister Abdullah said. A 13th man killed in the clash was from the former Soviet central Asian republic of Kyrgyzstan, he said.
Abdullah's report on the firefight, the worst violence in the Kabul area in months, appeared to clarify confused initial reports of Wednesday, including Afghan military statements that "Arab and Pakistani" gunmen had attacked an army position on the capital's southern edge.
The foreign minister, at a news conference called to present an official account of the bloodshed, said two soldiers also were killed. Initial reports had said two or three soldiers were killed, along with a civilian caught in a cross fire. The person identified as a civilian may have been one of the escaped Pakistanis
At one point, Abdullah said the 13 were "high-ranking members" of al Qaeda, but he offered no support for that, other than saying it came "from the investigation."
Afghan authorities were still investigating whether the prisoners had inside help in escaping from the National Security Department's Third Directorate detention center, he said.
The injured soldier was initially taken to a special forces base in Orgun-e in neighboring Paktika province, where he was operated on before being moved to Bagram.
He is likely to be further evacuated to Landstuhl Regional Medical Center in Germany on Thursday.
American soldiers wear bulletproof vests, but the round struck the soldier near the armpit, missing his ballistic protection.
The United States operates a special operations base in Lwara, very close to the Pakistani border. It has come under rocket attack in recent weeks, although no injuries have been reported.
An American soldier who hit an Afghan detainee has received the maximum punishment for the assault, including a reduction in rank, a military spokesman said Thursday.
The soldier from the 82nd Airborne Division was reduced two grades in rank from private first class to private E1, the lowest rank in the U.S. Army, said Maj. Gary Tallman at Bagram air base, the U.S. military headquarters.
He also must forfeit half a month's salary for two months, perform extra duty and face restrictions for two months, Tallman said.
U.S. military officials have reported a pronounced increase in attacks against coalition forces recently, after months of mounting operations to search for al Qaeda and Taliban remnants.
"This could be the closest thing to an offensive they can mount," King said. "We've got repeated small contacts."
Wednesday's violence in Kabul was the bloodiest in the capital since a U.S.-led military campaign drove the Taliban government from power in Afghanistan last December. It was the latest in a series of incidents to put the city on edge — including the assassination of a vice president in early July and the foiling of an alleged car-bomb plot in late July.
The National Security Department put that explosives-packed automobile and the accused would-be car bomber on display for the news media on Thursday, 10 days after the car was intercepted and the man arrested in central Kabul. Officials said his nationality had still not been determined, but he was neither Afghan nor Pakistani.
In Wednesday's deadly episode, the 13 detainees cut through the bars of a window at the detention center and escaped around 2 a.m., said Abdullah, who like many Afghans uses only one name.
After the nightly curfew was lifted at 3:30 a.m., they apparently walked to the south — in the direction of Pakistan — and around 6 a.m. were approached by soldiers from a nearby army post. The men opened fire and killed the two soldiers and wounded another, Abdullah said.
Soldiers at an adjacent army post — on a hill in the Bagram-i district in Kabul's southern outskirts — then fired on the attackers, who fled into a nearby village, where they took hostages but also met armed resistance from some villagers, Abdullah said. At some point, the men headed for a nearby mountain.
It was not clear how long they held hostages, but Abdullah said none was harmed during what military officials said was a three-hour running gunbattle.
Journalists later visiting the scene could see, from bloodstains and other evidence, that the men were finally trapped against the wall of an excavation at the foot of the mountain slope, and killed there. Abdullah said the military had sought their surrender, but "they resisted to the end," three of them even taking their own lives with grenades.
The foreign minister said the 13 all had been captured "after Sept. 11," that is, during or after the U.S.-led offensive that brought down the Taliban and scattered al Qaeda, blamed for the devastating U.S. terror attacks of Sept. 11.