Story highlights Three suicide car bombers and six gunmen attacked the base before sunrise, an official says

The International Security Assistance Force says initial reports put the toll at one

There were no immediate reports of any U.S. casualties

The Taliban claim responsibility for the attack

Three suicide car bombs were used to target a joint U.S.-Afghan base in eastern Afghanistan early Sunday in an attack that left at least three Afghan soldiers and two civilians dead, officials said.

The attack began shortly before sunrise when insurgents -- wearing coalition uniforms -- attacked three different points at Forward Operating Base Fenty, near the Jalalabad Airfield, according to the NATO-led International Assistance Security Force's regional command in Nangarhar province.

It's the latest in a series of attacks in recent years that have targeted the base, and it comes just months after NATO troops turned over security responsibilities for Nangarhar province to Afghan forces.

There were conflicting reports over casualties. ISAF said the attack, which it described as "complex," left at least one Afghan soldier dead and several wounded.

A provincial police spokesman put the toll at two civilians and three soldiers killed. At least 14 Afghan soldiers and four civilians were wounded in the blasts, said Havrat Hussain Mashriqwal, the police spokesman.

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There were no immediate reports of any U.S. casualties.

The attack began shortly after 5 a.m. when insurgents detonated a car bomb near the front gate of the base, according to Mashriqwal.

A second bomb-rigged car attempting to breach the base exploded after U.S. and Afghan troops opened fire, Mashriqwal said. A third car bomb was detonated outside the base's perimeter, according to the coalition.

"Afghan National Army and International Security Assistance Force soldiers repelled the attack and prevented any insurgent fighters from entering the perimeter, causing numerous insurgent casualties in the process," the statement said.

The insurgents -- three suicide bombers and six gunmen -- were killed in the blasts and the firefight that ensued, Mashriqwal said.

Taliban spokesman Zabiullah Mujahid claimed responsibility for the attack in a telephone call to CNN.

Mujahid said there were two suicide car bombs and a suicide bomber with an explosive belt used in the attack, which he claimed killed at least 20 people.

The Taliban routinely make telephone calls or send out e-mails claiming responsibility for attacks against coalition and Afghan troops.

The province borders Pakistan's volatile Khyber Pakhtunkhwa province, home to a number of insurgent groups, including members of the Haqqani Network.

Insurgents have been active in Nangarhar, which is home to the Tora Bora region -- where al Qaeda founder Osama bin Laden escaped after a 2001 battle with coalition forces.

Sunday's attack at FOB Fenty is the latest in a series to target the base and neighboring Jalalabad Airfield.

In February, nine people were killed and 12 wounded in a suicide bombing at the front gate of the base near the airfield. Two months later, four suicide bombers wearing women's burqas tried to launch an attack there, airfield commander Jahangir Azimi said at the time.

In June 2010, Taliban insurgents hit the front gate with a car bomb, rocket-propelled grenades and small arms fire.