At least two people were killed and as many as 10 wounded Wednesday in another attack on a Shiite mosque in Pakistan. Reports out of Rawalpindi, near the capital Islamabad, indicate a suicide bomber struck outside an imambargah -- a Shiite Muslim gathering place -- but failed to fully detonate his explosives. Security guards responded quickly, allowing most worshipers to stay safe inside the building, according to Geo News. The attacker died in the blast.

"When I heard the first shot, I locked the door and told worshipers to hide in the hall. People rushed inside to the mosque and saved themselves," witness Mohammad Yousaf told Geo News. The suspect reportedly threw a grenade outside the Qasar-e-Sakina imambargah but could not activate his vest. Windows were blown out from the explosion.

This is the fourth violent incident at a Shiite mosque in Pakistan, a majority Sunni country, so far this year. Bomb blasts killed about 10 people at a Rawalpindi imambargah on Jan. 10, about 60 in Shikarpur on Jan. 30 and 20 at a Peshawar mosque last Friday. Dozens more were wounded each time.

A spokesman for Jundullah, a Sunni extremist group associated with the Tehreek-i-Taliban in Pakistan, took responsibility for Wednesday's attack. Fahad Marwat told Reuters it was retribution for the armed forces' continued attempts to take control of North Waziristan, on the border with Afghanistan.

A witness told the Express Tribune that two people with the suspected bomber ran inside the mosque during Maghrib prayers. One was arrested, and authorities were searching nearby Wednesday for other people involved.

DawnNews identified the casualties as Ghulam Hussain and Abdul Shakoor, both of whom were standing outside the entrance of the congregation hall. Three people -- Mohammad Altaf, Syed Shaukat Hussain and Sajjad Hussain -- were critically wounded and being treated at the Pakistan Institute of Medical Sciences hospital.