PESHAWAR, Pakistan — Islamic militants disguised as policemen killed nine foreign climbers, including a U.S. citizen, Sunday in a brazen raid on their campsite at the base of one of the world’s tallest mountains.

The Pakistani Taliban asserted responsibility for the attack, calling it retribution for a suspected U.S. drone strike last month that killed Wali ur-Rehman, the second in command of the terrorist group.

“Through this killing we gave a message to the international community to ask U.S. to stop drone strikes,” said Ehsanullah Ehsan, a Taliban spokesman.

The attack in northern Pakistan at Nanga Parbat, the world’s ninth-tallest mountain, occurred around 1 a.m. as the climbers and their guides were at a camp about 4,000 feet above sea level. According to local and regional officials, about a dozen gunmen tied up the climbers’ Pakistani guides before shooting the climbers as they slept in tents.

The attackers reportedly wore police uniforms, an increasingly common tactic that Taliban militants have used to evade scrutiny.

In all, 10 people were killed, including five from Ukraine, two from China and one from Russia, according to preliminary information from Pakistani authorities. At least one Pakistani guide also was killed. At least one Chinese tourist survived and was rescued from the area, known as Fairy Meadows, officials said.

Pakistan’s interior minister said a U.S. citizen was killed in the assault. Interior Minister Chaudhry Nisar Ali Khan said four bodies have been identified, including those of a Chinese-American, two Chinese and one local guide who is thought to be a Nepali national.

Matthew Boland, acting spokesman for the U.S. Embassy in Islamabad, said authorities were withholding the identification of the American until next of kin could be notified.

“The United States government strongly condemns the terrorist attack on tourists in the northern areas of Pakistan in which nine innocent tourists and a Pakistani guide were murdered,” Boland said. “The U.S. Embassy Islamabad expresses its deepest condolences to the family and friends of the U.S. citizen and the other innocent tourists who were killed.”

The assault occurred in the picturesque Gilgit-Baltistan area, a popular tourist area in the Himalayas near the country’s border with China. Nanga Parbat rises to 26,660 feet. The world’s second-largest mountain, K2, with an elevation of 28,251 feet, straddles Gilgit-Baltistan’s border with China.

The slayings come as Pakistan’s military and government have been trying to combat a wave of terrorist bombings and sectarian attacks, including some aimed at Shiites in the northern part of the country.

Attacks on foreigners have been rare, and Sunday’s killings rattled Pakistan’s government.

Khan, the interior minister, spent part of Sunday fielding calls from worried ambassadors, including Chinese envoy Xu Feihong.

“He asked whether Chinese tourists were the target, and I said Pakistan was the target,” he said. “The terrorists want to give a message to the world that Pakistan is an insecure place and insecure country.”

Prime Minister Nawaz Sharif has vowed to rebuild Pakistan’s economy. He said such acts of “cruelty and inhumanity” wouldn’t deter the state from efforts “to make Pakistan a safe place for tourists.”

But Syed Mehdi Shah, the chief minister in Gilgit-Baltistan, said he worries that the incident will hurt the local economy, which relies heavily on the summer climbing season.

“It will have negative effects on tourism in the scenic northern areas, which is the sole source of revenue of the government as well (as) of the local population,” he said.

For weeks, Pakistan’s Taliban has been vowing that it would avenge the death of Rehman, who was killed May 29 when a suspected CIA-operated drone fired two missiles into a house in Pakistan’s North Waziristan tribal region.

U.S. officials have not confirmed that they carried out that strike, but they had issued a $5 million reward for Rehman’s capture after he was linked to a 2009 assault that killed seven Americans at a CIA training facility in Afghanistan.

At the time, the Pakistani Taliban partly blamed the Islamabad government for not doing more to stop suspected U.S. drone strikes on Pakistani soil.