KABUL, Afghanistan - Two U.S. soldiers were killed and six Americans were wounded yesterday in an early-morning rocket attack on the sprawling Bagram Air Field.

Military authorities said at least three rockets slammed into the base about 2 a.m. It was the third rocket or mortar attack to penetrate the base since January, but a rare instance of casualties being inflicted by such an attack.

The wounded, four service members and two civilians, were being treated at a medical facility on the base, which is the size of a small city.

Located along the fertile Shomali plain about 25 miles north of Kabul, the base and airfield are surrounded by farmland, desert, and towering mountains.

The three rockets hit separate areas of the base, and another exploded outside the security barrier, a military spokesman said. A police official in Bagram district, which surrounds the base, said he had heard no reports of Afghan civilian casualties.

"We offer our condolences and sympathy to the families of our two brave service members," said Army Maj. Gen. Curtis Scaparrotti, commanding general of Combined Joint Task Force-82 at Bagram. "Their sacrifice in the name of security and a better way of life for the Afghan people will not be forgotten."

It wasn't immediately clear if New York Times reporter David S. Rohde was at Bagram yesterday when the rockets hit.

Rohde escaped Friday from kidnappers in Pakistan, after more than seven months in captivity, and was flown Saturday to Bagram. Embassy officials gave him an emergency passport, and FBI officials were guarding him, a U.S. official said yesterday on condition of anonymity because he wasn't authorized to release the information.

A Taliban spokesman, Zabiullah Mujahid, claimed responsibility for the rocket attack. But Mujahid said the Taliban had no involvement in the kidnapping of Rohde and did not know anything about his escape.

The attack brought the U.S. death toll in Afghanistan this year to at least 81, according to www.icasualties.org, an independent Web site that tracks combat deaths.

At that pace, this year's total would eclipse the 155 U.S. deaths last year, the highest annual total since the U.S.-led invasion in 2001. The previous high was in 2007, when 117 U.S. troops died.

At least 94 U.S. troops have died in combat in Iraq this year, according to the Web site.

The attack came just hours after military spokesmen on Saturday announced three other U.S. combat deaths: two National Guard troops killed Friday by a roadside bomb in Kandahar, and a soldier killed Saturday by insurgents in eastern Afghanistan.

The Soviet-era Bagram base, which includes an airfield with several runways, is busy 24 hours a day. Thousands of U.S. and NATO soldiers, along with thousands of civilian contractors from several nations, can be seen walking the streets, shopping, and eating at fast-food outlets and an all-night coffee shop.

The Afghan residential areas around the base are relatively secure.

In February 2007, 23 people were killed by a suicide-bomb attack outside the base while then-Vice President Dick Cheney was visiting. The bomber did not penetrate a series of U.S.-manned security checkpoints leading into the main base. The Taliban claimed responsibility for that attack.

This article includes information from the Associated Press.