Islamabad, Pakistan (CNN) -- A suspected U.S. drone strike killed 20 people in North Waziristan, a region along the Pakistan-Afghanistan border, a Pakistani intelligence official told CNN Friday.
An officer from the political administration told CNN that six missiles struck a compound in Datakhel, an administrative division of North Waziristan. The region is known to be a hotbed for militancy and widely believed to be under little government control.
Both officials requested not to be identified because they are not allowed to disclose information to the media.
A military officer who requested anonimity for the same reason, told CNN that two drones were in the area, but only one of them fired.
In the incident, which occurred shortly after 10 p.m., two missiles struck the compound in the residential area followed by another four missiles that were fired 10 minutes later, the officer said. The death toll rose from nine to 20 as people who had gathered at the site after the first strike were hit in the second, the officer said.
It was not clear if any of the dead were civilians.
U.S. Secretary of State Hillary Clinton apologized this week for a coalition attack last November in which NATO fighter jets attacked a Pakistani checkpoint near the Afghanistan border, killing 24 Pakistani soldiers.
U.S.-Pakistan relations soured after the incident, which led Pakistan to close supply routes for NATO trucks carrying supplies to Afghanistan.
After the apology, Pakistani leaders reopened the routes through Pakistan's western border.
Islamist political parties expressed outrage at their reopening, accusing the government selling out to U.S. demands and disregarding the will of its own parliament.
Pakistan's parliamentary committee on national security passed a resolution in April that set the cessation of drone strikes as a condition for the reopening of supply routes to Afghanistan.
Pakistan will continue to press the U.S. administration to stop drone attacks, Qamar Zaman Kaira, Pakistan's minister for information and broadcasting, said after the Clinton apology.
Pakistani government officials have been angered by suspected U.S. drone airstrikes in the country that have left many dead.
The U.S. military routinely offers no comment on reported drone strikes.