Islamabad , Pakistan ( CNN ) -- A three-day mourning period began Friday in a southwestern Pakistani province where a series of bomb blasts killed nearly 100 people the previous day in the bustling city of Quetta . The deadliest explosions were two suicide bombings in a predominantly Shiite neighborhood known as Alamdar Road . One blast brought police , rescue workers and journalists rushing to the scene . It was swiftly followed by another explosion -- set off by a man sitting in a car with over 100 kilograms of explosives -- that caught many of those responding to the initial attack . The double bombing , described by police as one of the worst attacks on the Shiite minority , killed 85 people and wounded about 150 . Lashkar-e-Jhangvi , a banned Sunni militant group , claimed responsibility for the Alamdar Road attacks . Shiites , a minority sect in the mainly Sunni Muslim Pakistan , face persecution from extremists . Last month , more than 20 Shiite pilgrims were killed when a car bomb detonated near the buses they were traveling in . Mir Zubair Mehmood , a Quetta police official , said the Alamdar attacks were motivated by Sunni and Shiite sectarian differences . Read more : What 's working in Pakistan . Another blast in Quetta on Thursday struck a security checkpoint in a busy market , authorities said . A bomb planted in a car detonated as security forces entered the area , killing 12 people and wounding 45 , according to Wazir Khan Nasir , a police spokesman . Nasir blamed the attack on Baloch insurgents . A fourth bomb went off by the side of the road leading to the city 's airport , wounding three . Quetta is the capital of Balochistan province . Watch : Pakistan : Give us the drone technology . Balochistan Chief Minister Nawab Raisani announced the mourning period for the province late Thursday in the aftermath of the bombings . Over the next three days , commercial activity in Quetta , one of Pakistan 's largest cities , will be suspended . Balochistan is regularly plagued by violence from myriad causes . As well as the sectarian attacks on Shiites , the unrest in the province is believed to be fomented by several insurgent groups , including the separatist Balochistan Liberation Army and the Pakistani Taliban . Although Balochistan is the largest province in Pakistan geographically , analysts and some locals have criticized the federal government for neglecting it , leading to instability . More on Pakistan : India and Pakistan trade accusations over Kashmir violence . Prime Minister Raja Pervez Ashraf condemned the blasts in Quetta . `` The prime minister , while expressing his heartfelt condolences and sympathies with the bereaved families , reiterated the government 's resolve to stamp out the menace of militancy and terrorism from the country in its all shapes and manifestations , '' said a statement released by his office . Read more : Malala , others on front lines in fight for women . Elsewhere on Thursday , a bomb went off in a preaching center on the outskirts of the city of Mingora in the Swat Valley , police said . The blast killed 21 people and wounded 70 , according to Dr. Jamil Khan , a doctor at Mingora hospital . So far , no group has taken responsibility for the attack . Mingora is in Khyber-Pakhtunkhwa province in Pakistan 's northwest . The U.S. ambassador to Pakistan , Richard Olson , expressed condolences to the families of those killed in the attacks . `` The United States stands with the people of Pakistan in strongly condemning these senseless and inhumane acts , '' he said in a statement released Friday . CNN 's Aliza Kassim in Atlanta and journalist Nasir Habib in Islamabad contributed to this report .
NEW : Baloch insurgents are blamed for one attack ; Pakistani militants , for a double-bombing . Police say the death toll from the bomb blasts in Balochistan has risen to 97 . A separate attack in Kashmir kills one people . A the next three days mourning period begins in the restive province of Balochistan .