India, Feb. 6 -- Minutes before the blast that has now claimed at least 31 lives, worshippers were gathered for Friday prayers at a Shiite imambargah in Islamabad when a suicide bomber detonated explosives at the entrance of the mosque.

Police sources said the attacker was intercepted by security guards at the main gate of the imambargah but managed to detonate himself after running at least 20 metres inside the premises, AFP reported.

However, eyewitnesses have said that the terrorist was stopped at the main entrance of the religious site, which is when the terrorist start firing.

"He then ran inside at least 20 metres, and as the prayer was underway, he blew himself up," Geo News cited the eyewitnesses as saying.

The explosion occur...