ISLAMABAD, Feb 8, (AP): Pakistani security forces raided multiple locations and arrested four suspects, including the alleged mastermind, behind a suicide bombing at a Shiite mosque on the outskirts of the capital that killed 31 people, the interior minister said Saturday. The announcement by Mohsin Naqvi came a day after a regional affiliate of the Islamic State group, identifying itself as Islamic State in Pakistan, claimed responsibility in a statement carried by its Amaq News Agency.

The statement said the attacker on Friday opened fire on security guards who tried to stop him at the main gate before detonating his explosive vest after reaching the mosque’s inner gate. The IS group suggested it viewed the Pakistani Shiites as legitimate targets, calling them a "human reservoir” that provided recruits to Shiite militias fighting IS in Syria.

Friday’s mosque bombing that also wounded 169 people was the deadliest in Islamabad since a 2008 suicide bombing at the Marriott Hotel that killed 63 people and wounded more than 250. In November, a suicide bomber struck outside a court in the capital, killing 12 people. Naqvi described the suspected mastermind of the bombing as an Afghan linked to IS.

He alleged the attack was planned and the bomber trained in Afghanistan with financial backing from India- claims for which he provided no immediate evidence. There was no immediate comment from New Delhi and Kabul. Naqvi also alleged that several militant groups were operating from the Afghan territory to launch attacks against Pakistan and urged the international community to take notice, warning that instability could spread beyond the region.

Addressing public concerns about security lapses, he said, "If one blast happens, 99 others are being foiled as well.” Earlier, more than 2,000 grief-stricken mourners gathered as coffins of those killed were brought to the same mosque for funerals of about a dozen victims, joined by Shiite community leaders and senior government officials. Funerals of other victims were to be held in their hometowns.