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 CIA base in southeastern Afghanistan last month. But a Taliban spokesman said 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 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. American officials have been trying to kill Mehsud with drone strikes, but they rarely discuss the attacks and would not immediately confirm whether he had been the target of the attack or killed. Mehsud became leader of the Pakistani Taliban in 2009, succeeding the previous chief, Baitullah Mehsud, who died in an American drone strike in South Waziristan in August. Hakimullah Mehsud, a member of the same tribe, had been the target of at least one earlier airstrike, according to American and Pakistani officials. Last April, Hakimullah Mehsud escaped unhurt when an American missile struck a militant training camp in northwest Pakistan. A video released last week showed him seated next to Humam Khalil Abu Mulal al-Balawi, the Jordanian who carried out the Dec. 30 bombing of the CIA base in Afghanistan. The men claimed that the attack was retribution for the killing of Baitullah Mehsud. 