A bomb blast killed at least 11 people and wounded another 50 on Wednesday in a northwest Pakistani tribal region where many Taliban militants are believed to have gathered after fleeing an army offensive, officials said.

The explosion at a cattle market in Orakzai tribal region came as U.S. special envoy Richard Holbrooke met with Pakistan’s prime minister in the capital, Islamabad, to discuss ways to enhance the countries’ cooperation in the battle against militancy.

Local government official Liaquat Khan said at least 50 people also were wounded in the Darmela area of Orakzai. Officials were still investigating whether the explosion was caused by a suicide bomber or a planted device.

Pakistan has suffered numerous bombings over the last few months, many of them apparently in retaliation for the army operation in the South Waziristan tribal region. Though militants tend to target security forces, many of the recent attacks have been at civilian-heavy sites, includings markets catering to women and children.

The Pakistani military has carried out airstrikes against several targets in Orakzai in recent weeks after it appeared many Pakistani Taliban fighters had fled there from South Waziristan.

The latest blast also comes just days after it was revealed that a joint Pakistani-CIA operation had captured the Afghan Taliban’s No. 2 official, Mullah Abdul Ghani Baradar, in the southern Pakistani city of Karachi.

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