A U.S. Army Green Beret was killed by hostile fire in eastern Afghanistan Friday. He became the first member of the U.S. military to be killed by the enemy since the U.S. campaign began Oct. 7.

The soldier, Sergeant First Class Nathan Chapman of San Antonio, Texas, was killed in a gun battle in the vicinity of Khost, near the Pakistan border. Chapman was 31 years old.

Officials say Chapman was meeting with Afghan tribal leaders when he was ambushed and killed by small arms fire.

Gen. Tommy Franks, commander of U.S. Central Command, announced the death at a news conference in Tampa, Fla. The soldier's name was released later, after his family was notified.

A CIA paramilitary officer accompanying Chapman on the mission was seriously wounded in the same skirmish and was receiving medical attention, a U.S. official told Fox News. The official said the agent's prognosis was good.

Green Berets, sometimes with CIA officers, are coordinating intelligence-gathering efforts and searching caves and bunkers with local Afghans.

Franks said the death underscored the dangers faced by U.S. and allied forces in Afghanistan, where there are pockets of resistance from Al Qaeda and Taliban fighters.

"There was an exchange of small-arms fire," Franks said. "This American serviceman was doing his job. He was out for the purpose of working with and coordinating with tribal leaders in that area."

The special-ops trooper became the fifth American to die in Afghanistan and the seventh to die in the U.S. campaign.

On Nov. 25, CIA agent Johnny "Mike" Spann was killed during a prison uprising in the northern city of Mazar-e-Sharif. On Dec. 5, three Green Berets were accidentally killed in a U.S. airstrike outside Kandahar. Two U.S. military members were killed in a helicopter crash in Pakistan early in the military campaign.

Pentagon officials have stressed frequently that although the large-scale fighting in Afghanistan is over, the country remains dangerous for U.S. troops, who now number about 4,000 on the ground.

Franks told reporters at Central Command headquarters that the mission in Afghanistan is still "dangerous work indeed."

Afghanistan "is still an extraordinarily dangerous place and this is an extraordinarily dangerous mission," Victoria Clarke, chief spokeswoman for Defense Secretary Donald H. Rumsfeld, told reporters Friday before the combat casualty was disclosed by other officials.

U.S. warplanes bombed a suspected Al Qaeda base in eastern Afghanistan for the second time in as many days Friday after coalition observers detected some of Usama bin Laden's forces trying to regroup there, military officials said.

The second strike on the Zawar Kili camp near Khost took place in late morning, after coalition forces detected some activity at the base in the hours following the first strike, Clarke said.

The Associated Press contributed to this report.