ISLAMABAD, Pakistan — Three missiles thought to have been fired from remotely piloted American aircraft struck a Taliban training camp in northwestern Pakistan and killed 21 militants, according to a local government official and news reports on Friday.

Fifteen other people were wounded in the strike, from about 9:30 p.m. to 10 p.m. on Thursday, on a training camp some 20 miles from Parachinar, the capital of the Kurram tribal area, according to the official, who spoke on the condition of anonymity.

The camp was under the command of Fazal Saeed, a local militant commander aligned with the Pakistani Taliban leader Baitullah Mehsud. On Friday evening, the official said the dead were all militants.

The attack was the sixth on Mr. Mehsud’s camps in the tribal areas since President Obama took office, expanding the covert war run by the Central Intelligence Agency and carried out largely by remotely piloted aircraft.