(CNN) -- Shiite Muslims in the Pakistani city of Quetta are refusing to bury scores of people killed in a devastating weekend bombing until authorities respond to their demands to take military action against the Sunni extremists behind the attack. The macabre protest is an expression of the anger and frustration among Shiites in the southwestern province of Balochistan, whose capital is Quetta, over the government's failure to shield them from a series of bloody sectarian attacks in recent months. The outlawed Sunni militant group Lashkar-e-Jhangvi has said it carried out the attack Saturday in Quetta in which police say a suicide bomber rammed a water tanker laden with explosives into a crowded marketplace, setting off a huge blast that killed more than 80 people and wounded at least 180 others.