At least 31 people died and many others were injured in a suicide blast at Imambargah Qasr-i-Khadijatul Kubra on the outskirts of Islamabad during Friday prayers. The attacker was stopped at the gate by volunteers and exploded himself, a security source told AFP. Worshipper Muhammad Kazim, 52, described the explosion as "extremely powerful" as prayers had just begun. Another witness, Imran Mahmood, said there was a gunfight. He said, "The suicide attacker was trying to move forward, but one of our injured volunteers fired at him from behind, hitting him in the thigh." The attacker then "detonated the explosives", Mahmood added. This incident is the deadliest attack in Islamabad since the 2008 Marriott hotel suicide bombing. Investigators identified the bomber, whose severed head was found, as a resident of Gunj in Peshawar's walled city. Forensics used the Nadra database to confirm his identity. Early investigations suggest he was linked to the IS militant group and had traveled to Afghanistan multiple times. Authorities are questioning the bomber's family and relatives in Peshawar. Geo-fencing and CCTV footage are being used to track suspects. Police confirmed progress in the investigation and said raids are ongoing. Some relatives of the bomber have been detained in Nowshera. Funerals for some victims are scheduled for Saturday.