Meanwhile, Kabul was shaken Wednesday by powerful explosions of oil and gas tankers at a depot on the northeastern outskirts of the capital. Stores and homes were devastated, leaving at least three people dead and more than 80 injured, according to police and hospital officials.
Police said they had not identified the exact cause of the explosions, including whether it was accidental or related to extremist activity.
The blasts hit midafternoon at the depot of the Haidarzada Gas & Oil Co. and sent black clouds and flames billowing over the district, a mixture of residential areas and small business parks.
A spokesman for the International Security Assistance Force, as the coalition is formally known, said Tuesday's attack on the coalition troops occurred in the evening at a joint Afghan army-coalition base in the Sayed Abad district of Wardak province.
U.S. Air Force Capt. Dan Einert, an ISAF spokesman, told McClatchy Newspapers the five soldiers were all taken to a coalition medical facility for treatment. "They're all stable at this time," Einert said.
The Afghan soldier who shot them escaped, Einert said. He added that there was no indication of what precipitated the shooting.
ISAF declined to confirm the nationality of the wounded soldiers. Shahidullah Shahid, a spokesman for Wardak's governor, said they were Americans.
"A man wearing an Afghan army uniform went into an ISAF base in the Hashim Khel area of Sayed Abad and opened fire on the American troops ... before running away," Shahid said.
A senior Afghan security official told McClatchy that the attacker was an Afghan soldier from northern Kunduz province. "It was 7 in the evening when he entered the base - a time when [the American troops] were doing sport or relaxing," the official said. He declined to be named because he was not authorized to discuss the case with reporters.
The Taliban in a website statement listed the attacker as Mohammad Wali.
"The soldier has been with the puppet army based at the invader's base for a long time," the statement said, referring to the Afghan army and coalition troops. "He is now safely out of the area and has joined the local mujahedeen," or Islamic holy warriors, as the Taliban refer to themselves.
Twenty-six coalition soldiers have been killed in 19 "green on blue" attacks this year. Last year, 35 were killed in 21 incidents, according to coalition figures.
This article contains information from the New York Times News Service.
