A suspected US missile strike near Pakistan's border with Afghanistan on Saturday killed at least five people, an intelligence official said.
Missiles believed to have been fired from US-operated pilotless aircraft targeted an abandoned government school in the Sararogha area of the South Waziristan tribal district.
The building was allegedly being used by local Taliban militants as a training facility.
"According to preliminary figures, five people have been killed and around a dozen more injured," the official said on condition of anonymity.
The official said identities of the dead could not be confirmed immediately.
South Waziristan is considered a sanctuary of Al Qaeda and Taliban fighters, and is also home to top Pakistani militant commander Baitullah Mehsud.
Mehsud has been blamed for a series of attacks throughout the country, including the December 2007 gun-and-bomb attack in the garrison town of Rawalpindi which killed former prime minister Benazir Bhutto.