It said a clearance operation was underway and “the perpetrators of this heinous and cowardly act will be brought to justice.”
There was no immediate comment from New Delhi or the BLA, which often targets security forces and civilians and foreigners in Balochistan and elsewhere.
President Asif Ali Zardari and Prime Minister Shehbaz Sharif, in separate statements, denounced the attack and praised security forces for sacrificing their lives in the war against extremism.
The latest attack came less than two months after a deadly assault by the BLA on a passenger train in Balochistan that killed 31 people, most of them soldiers.
Balochistan has long been the scene of a low-level insurgency, with several separatist groups carrying out attacks primarily targeting security forces. The insurgents demand independence from the central government.
The Pakistani Taliban and the Islamic State group also have a presence in the province.