Some 20 people have been killed in a U.S. drone strike in north-western Pakistan, local television channels have reported.

A U.S. drone fired six rockets on Friday at a house in the town of Miran Shah, in the North Waziristan tribal region, where Taliban militants were believed to be hiding, reports said.

The strikes came just days after Pakistan agreed to reopen supply routes that the United States and its allies have used to supply their troops in Afghanistan.

Pakistan closed the routes last November after a U.S. airstrike killed 24 Pakistani soldiers in at a remote outpost near the Afghan border.

On Tuesday, U.S. Secretary of State Hillary Clinton said the United States was “sorry for the losses suffered by the Pakistani military.” The statement came after months of protracted negotiations between U.S. officials and the Pakistani government, which has been seeking a formal U.S. apology for the airstrike as a condition of reopening the supply routes.

Islamabad has repeatedly criticized U.S. drone strikes on its territory as a violation of Pakistan’s sovereignty.