A bomb exploded at a compound in northwest Pakistan today, killing nine people and wounding 20, local government and intelligence officials said.
The bombing in the compound, used by a local militia and containing residential units and an office, occurred near the village of Spin Tal in the Orakzai tribal region.
The Pakistan military has been conducting operations against militant groups in the area for months.
"We are not sure if a suicide bomber hit the compound or if some militants were assembling a bomb and it accidentally went off," a local government official said, requesting anonymity.
The wounded were evacuated to a hospital in neighbouring Hangu district. A hospital official said several of the wounded were in critical condition.
Several militant groups are active in Pakistan's northwestern semi-autonomous tribal regions, near the border with Afghanistan, including the Pakistan Taliban, responsible for many of the bombings across the country in recent years.