A Pakistani security official told The New York Times the drone hit a compound now occupied by militants from Tajikistan.
The compound is in a village near Mir Ali, an al-Qaida and Taliban stronghold.
"Militants are clearing the rubble and pulling out the bodies," the official said. "These are preliminary reports. We do not know the identity of those killed as yet."
The Bureau of Investigative Journalism said the strike was the 18th in the tribal areas in 2013 and the first since July 28, when a strike hit near the border with Afghanistan.