The military helicopter crashed into a school with children inside and set the building ablaze.
The Pakistani Taliban today claimed responsibility for shooting down a military helicopter, killing six people including the Norwegian and Philippine envoys, and said Prime Minister Nawaz Sharif was their target.
"The helicopter was shot down by an anti-aircraft missile, killing pilots and many foreign ambassadors," an Urdu-language statement emailed by their main spokesman Muhammad Khorasani said.
It was not immediately possible to verify the claim, but the Gilgit-Baltistan region in Pakistan-Occupied Kashmir, where the chopper came down, is not known as a stronghold for the militant organisation.
Prime Minister Nawaz Sharif was travelling to the mountainous northern region of Gilgit on a separate aircraft to launch two projects when the accident happened. He returned to Islamabad, his office said.
The military helicopter crashed into a school with children inside and set the building ablaze, the army said as officials warned that casualties could rise.
The helicopter was one of three carrying a delegation of envoys to inspect projects on a three-day trip to the Gilgit-Baltistan territory where they were set to meet with Prime Minister Sharif.
Leif H Larsen, the Norwegian envoy, and Domingo D Lucenario Jr of the Philippines were killed along with the wives of the Malaysian and Indonesian ambassadors, as well as the helicopter's two pilots, according to official tweets by the army.
Polish ambassador Andrzej Ananiczolish and Dutch ambassador Marcel de Vink were also injured, the army added.
It was the worst air crash since 2012 when a civilian 737 went down in Islamabad, killing 130 people.
A senior local administrative official said: "We have been told to send in as many ambulances as we can because the situation there is 'urgent'".
Known for its spectacular mountain ranges and unique culture, Gilgit-Baltistan is a strategically important region that borders China and Afghanistan.