QUETTA - No significant progress has been made in the investigation of Mastung tragedy that left 26 Shia pilgrims dead. Unidentified gunmen attacked a Taftan-bound passenger bus at Ganjdori area of Mastung on September 20, killing 26 Shia pilgrims. Though the law enforcement agencies have arrested more than 250 suspects from Quetta and other parts of Balochistan, there is no significant progress in the investigation, an official said on the condition of anonymity. He said, Since no proper measures have been taken to bring the culprits to justice, the incidents of sectarian killing surge. Though police and other law enforcement agencies have arrested more than 250 people from Quetta and Mastung in connection with the killing of pilgrims, another incident took place in Quetta just four days after the tragedy, claiming three lives, said the source, adding that just arrests could not stop the sectarian killings. Reportedly, Balochistan, once a peaceful province, plunged into lawlessness and sectarian strife after the takeover of former president Musharraf. According to statistics, more than 400 people, mostly from the Hazara tribe, have lost their lives in sectarian killing in the Quetta city. Only one person fell prey to sectarian violence before the takeover of former president Pervez Musharraf, said a source in the Balochistan Home Department. Quetta witnessed a surge in sectarian killings after the murder of two Sunni leaders in Julys last week and the mid of August this year. Eleven people from the Hazara tribe were killed a day after the murder of Maulana Abdul Karim Mengal. Forty-eight people of the Hazara tribe have been killed in six weeks in five separate sectarian attacks, including a suicide hit on Eidul Fitr and firing on pilgrims in Mastung, the source added. This situation has raised worries amongst the people and sources in police department warned that the situation would worsen if serious measures were not taken to stamp out sectarianism.