Bagram, Afghanistan ? Gunmen attacked U.S. and Afghan troops in eastern Afghanistan, touching off a firefight that wounded one American soldier, a U.S. military spokesman said Wednesday. Three U.S.-allied Afghan fighters were killed, Afghan officials said.

The incident took place Tuesday night at the airfield near the volatile town of Khost, about 40 miles east of fighting in the recently concluded Operation Anaconda.

“Last night, terrorists using machine guns, rocket-propelled grenades and mortars attacked coalition forces in Khost. We returned fire and continue to develop the situation as we speak,” said Maj. Bryan Hilferty, spokesman for the 10th Mountain Division, at Bagram air base north of Kabul.

U.S. troops and their Afghan allies called in air support from an AC-130 gunship and a B-1 bomber, which illuminated the area with flares, U.S. Central Command said in a statement.

Three U.S.-allied Afghan fighters died in a raid on a checkpoint just outside the airport, said Fazal Mir, a local leader and supporter of Afghanistan’s interim government. No other details were available and U.S. officials declined to comment.

One U.S. soldier with the 101st Airborne Division was shot in the arm, but the injury was not considered life-threatening, said Commander Frank Merriman, spokesman for U.S. Central Command.

Hilferty would not say how many U.S.-allied troops were in the area. U.S. special forces teams have been operating in Khost, located near the Pakistan border, for some time.

It was unclear whether the attackers were among surviving al-Qaida and Taliban fighters who escaped Operation Anaconda, he said.

The operation was launched March 2 to clear the eastern Shah-e-Kot Valley of al-Qaida and Taliban fighters. Gen. Tommy Franks declared the operation over Monday and deemed it a success, although Afghan commanders said most of the al-Qaida and Taliban fighters escaped.

U.S. military officials have said the war in Afghanistan will continue as long as al-Qaida and Taliban forces remain active in the country.

Tensions have been running high for months in Khost, which used to contain several al-Qaida training camps for Kashmiri separatists. On Tuesday, gunmen angry over the appointment of the local police chief exchanged gunfire with security forces in the main town market, killing one person and injuring three others.

U.S. special forces came under fire at the Khost airport at the beginning of Operation Anaconda but there were no injuries. On March 10, three Afghans from a tribe allied with the United States were gunned down in a drive-by shooting in front of the local government office.

On Jan. 4, gunmen fired on U.S. special forces traveling through the town, killing Sgt. 1st Class Nathan Chapman, the first American soldier to die by hostile fire in Afghanistan.

After the 1998 bombings of U.S. embassies in Kenya and Tanzania, the United States fired Tomahawk missiles at an al-Qaida camp near Khost in a failed bid to kill suspected terrorist mastermind Osama bin Laden.

Meanwhile, Pakistani security forces arrested seven people suspected of being al-Qaida members as they tried to slip across Pakistan’s border into Afghanistan, a senior government official said Wednesday.

The Pakistani border guards became suspicious of the men during a routine search in Kurram, roughly 130 miles southeast of Peshawar. The area is just across the border from the area where U.S.-led forces conducted Operation Anaconda.

Authorities seized three pistols and an undisclosed amount of cash from the men, who came from Uganda, Sudan, Mauritania and Pakistan.