Pakistani security forces have arrested four suspects linked to a suicide bombing at a Shiite mosque near the capital that killed 31 people. The interior minister announced the arrests on Saturday, including the alleged mastermind. A regional affiliate of the Islamic State group claimed responsibility for Friday's attack. The bombing, which also wounded 169 people, was Islamabad's deadliest since 2008. The alleged mastermind is described as an Afghan linked to IS, with claims of financial backing from India. The attack has drawn international condemnation, and Pakistan's prime minister emphasized the importance of global support for counterterrorism efforts.