Four people have been arrested on suspicion of facilitating a suicide bombing that killed more than 30 people on Friday, Pakistan's interior minister has said.

Mohsin Naqvi stated that an Afghan national, who is alleged to be the mastermind behind the attack, was among those detained. One counter-terrorism officer was killed and three more were wounded during the raids to arrest the suspects, he added.

The Islamic State group has claimed responsibility for the bombing that targeted Friday prayers at the Shia mosque in the Tarlai area, packed with worshippers.

More than 160 individuals were injured in the blast, which has been identified as the deadliest in the capital for over a decade.

Thousands gathered in Islamabad to mourn the 32 victims of the attack, as security was heightened with soldiers standing guard and police checkpoints established across critical areas. Prime Minister Shehbaz Sharif expressed his profound grief over the incident, labeling it a crime against humanity.

Eyewitnesses recount terrifying moments during the explosion, while memorials filled the streets as the city collectively mourned. Naqvi also accused India of funding the attackers, claims that India's foreign ministry has strongly denied.

Pakistan's Defense Minister hinted at possible involvement from Afghanistan, prompting an outcry from the Afghan Taliban government, which denounced the accusations as unfounded.

In response to the attack and rising tensions, Naqvi has pledged to bolster security in Islamabad by increasing the number of police officers.

This tragic event comes on the heels of a violent week in Pakistan that saw significant casualties, highlighting ongoing security challenges in the country.