About 14 to 16 militants targeted the camp at Buner Valley in Gilgit-Baltistan that serves as a base for mountaineers headed for the 8,126-metre Nanga Parbat, the world's ninth highest peak.
The attack was carried out late last night but authorities were alerted only this morning.
For hours, confusion surrounded the number and nationality of those killed in the attack in Gilgit-Baltistan, a territory disputed between India and Pakistan.
A hospital spokesman said all the foreigners were killed by gunshot wounds in the head.
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Officials initially said nine foreigners and one Pakistani were killed. They later revised the toll to 11, including two Pakistanis.
Late at night, other officials said 10 foreigners and a Pakistan were killed.
Earlier in the day, Interior Minister Chaudhry Nisar Ali Khan said in parliament that another Chinese tourist was recovered safely.
The Gilgit Scouts is a paramilitary unit that is part of the Army's Northern Light Infantry regiment.
The outlawed Tehrik-e-Taliban Pakistan claimed responsibility for the attack, saying it was carried out to avenge the death of the group's deputy Chief, Waliur Rehman, in a US drone strike on May 29.
Taliban spokesman Ihsanullah Ihsan called journalists and said the attack was carried out by a new faction named Junood-e-Hafsa.