Islamabad, Pakistan (CNN) -- A suspected U.S. drone fell on Pakistan's tribal region overnight, two Pakistani senior security officials told CNN on Sunday.
The drone fell in the northern part of South Waziristan -- one of the seven districts of Pakistan's volatile tribal region bordering Afghanistan -- said the security officials, who did not want to be named because they are not authorized to speak with the media.
The officials said parts of the drone are in the Pakistani military's custody. They said they did not know why the drone fell.
Last month, another drone fell in the Chaman area of Balochistan province, near the Pakistani-Afghan border.
The United States rarely comments on drone operations.