Four people have been arrested for helping a deadly suicide bombing at a Shia mosque in Islamabad, Pakistan. The attack on Friday killed 32 people and injured more than 160 during crowded Friday prayers. Pakistan's interior minister, Mohsin Naqvi, said the suspects include an Afghan national who masterminded the blast. One counter-terrorism officer died and three were hurt while arresting the suspects. The Islamic State group said it carried out the bombing. Huge crowds gathered on Saturday for funerals, with heavy security in place. Prime Minister Shehbaz Sharif said he feels "deep grief" over the attack. President Asif Ali Zardari called it "a crime against humanity." Naqvi accused India of funding the attackers, but India denied all allegations as "baseless." Pakistan’s Defence Minister Khawaja Asif suggested Afghanistan's involvement, which the Afghan Taliban called "regrettable" without any proof. Naqvi promised to boost Islamabad's security by adding police and improving smart security systems. This blast is the deadliest in the capital in over 10 years. It follows a violent week where 58 civilians died in Balochistan, blamed on the Balochistan Liberation Army. The military said it killed over 200 militants after those attacks.