ISLAMABAD, Pakistan  At least 10 people were killed in an American drone strike in northwest Pakistan on Thursday morning that was aimed at the leader of the Pakistani Taliban, according to Pakistani security officials.

After the attack, several Pakistani security officials said there was no word on the whereabouts or condition of the Pakistani Taliban leader, Hakimullah Mehsud, who claimed responsibility for a suicide attack that killed eight people at a C.I.A. base in southeastern Afghanistan last month. But a Taliban spokesman said Mr. Mehsud was not among the casualties.

“The important thing for us is whether Hakimullah is among those killed,” said a Pakistani official in South Waziristan.

A Pakistani intelligence official said he believed that Mr. Mehsud was “definitely targeted” in the attack, which struck a compound in a remote region near the border of the tribal regions of North and South Waziristan about 7 a.m. Thursday.