The strike elicited a swift condemnation by Pakistan's government, which released a statement saying the strikes are a violation of its sovereignty.
The strike in the Sarai Darpa Khel area of the North Waziristan tribal region also wounded two suspected militants, said the officials, speaking on condition of anonymity because they were not authorised to talk to the media.
The suspected militants who were targeted were believed to be from the Afghan Haqqani network.
US officials consider the Haqqani network to be one of the most dangerous militant factions fighting American troops in neighbouring Afghanistan.
The leadership of the Haqqani network pledges allegiance to Taliban chief Mullah Omar but operates fairly independently.
US drone strikes have become a serious source of tension between Washington and Islamabad.
Pakistan's government regularly denounces the strikes as a violation of the country's sovereignty, even though senior officials are known to have supported some of the attacks in the past.
"The government of Pakistan has consistently maintained that drone strikes are counter-productive, entail loss of innocent civilian lives and have human rights and humanitarian implications," the ministry of foreign affairs said in a statement on Wednesday.
"These drone strikes have a negative impact on the mutual desire of both countries to forge a cordial and cooperative relationship and to ensure peace and stability in the region," the ministry said.
US officials rarely provide details publicly about the covert CIA drone programme in Pakistan.
Elsewhere in north-west Pakistan, militants attacked a police post before dawn on Wednesday and killed six police officers, said a local government administrator, Habibullah Khan.
Another 10 police officers were wounded in the attack about 25km south-east of the city of Peshawar, said another government official, Feroz Shah.
The post was staffed by both paramilitary police from the Frontier Constabulary force and also by tribal police officers.
Khan said police officers retaliated in a gunbattle that lasted several hours and killed several militants. No one has claimed responsibility for the attack.
But the Pakistani Taliban have carried out many similar attacks against security personnel in the area. – Sapa-AP