KABUL, Afghanistan (CNN) -- A car bomb detonated Friday morning outside a U.S. military base in Kabul, wounding more than 20 NATO soldiers, civilian contractors, and Afghans, according to NATO.

Initial reports that two Afghans were killed in the attack were later recanted by the military source who provided the information to CNN.

The Taliban claimed responsibility for the attack, saying it was a suicide car bombing. The attack happened at approximately 8 a.m. local time near a checkpoint outside the perimeter of Camp Phoenix located on the outskirts of Kabul, NATO spokesman Sgt. Kevin Bell said.

Nine members of NATO's International Security Assistance Force, 10 civilian contractors, and several Afghans were wounded, NATO said in a news release. The nationalities of the ISAF service members and civilian contractors were not released.

"The insurgents use indiscriminate attacks like this to attempt to intimidate international forces and our Afghan partners, but we will continue our important efforts in support of the Afghan people," said ISAF spokeswoman Navy Capt. Jane Campbell.

Camp Phoenix houses mostly U.S. troops who are helping train Afghan police and army forces.

Taliban spokesman Zabiullah Mujahid claimed responsibility for the attack, saying that an attacker from Paktia province carried out the operation.

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