Pakistani officials say NATO helicopters from Afghanistan have attacked a military checkpoint in northwest Pakistan, killing 25 troops and wounding seven others.

A Pakistani military spokesman said the pre-dawn attack Saturday in the Mohmand tribal area near the Afghan border was “unprovoked and indiscriminate.”

Pakistan has closed NATO's supply route through the country following the airstrike.

A NATO spokesman in Kabul says the international coalition is aware of an “incident” and would release more information after gathering more facts about what happened.

U.S. officials have said Pakistan's tribal belt provides sanctuary to Taliban who have been fighting for 10 years against U.S. troops in Afghanistan.