Pakistani security forces today said they had killed the Islamic State-linked mastermind of last week's bloody suicide bombing that left 149 people dead in the restive Balochistan province. Those killed in the Mastung blast included an election candidate, creating a major threat for those involved in the general election to be held on July 25. Officials said that paramilitary Frontier Corps (FC) tracked down Islamic State (IS) operative Hidayat Ullah in a house of village Darenjo in Kalat district. \u201cHe offered resistance but was killed in the shootout,\u201d Kalat Deputy Commissioner Qaisar Khan said. A security official said that Ullah had aided the suicide bomber Hafeez Nawaz. A police probe revealed that Nawaz belonged to Thatta district of Sindh province. The security situation in the Balochistan has deteriorated ahead of polls. At least six people were injured today in a roadside bombing in Chaman area.