More than 30 Shia Pakistani worshipers were killed and more than 50 wounded in a devastating suicide attack today outside a mosque in the town of Dera Ghazi Khan in the central Pakistan province of Punjab.

The bomber detonated in the midst of a procession of Shia mourning the death of Imam Hussein, the grandson of the Prophet Mohammed and a central figure of Shia Islam. The bomber detonated just outside of the Johar Ali Imam Bargah mosque as the procession returned. Police are certain the bombing was a suicide attack as no crater was left at the scene of the attack. Casualties may rise as officials are still assessing the attack scene and many of those wounded are in critical condition.

The attack took place in Punjab province, well outside of the Northwest Frontier Province where the Taliban is fighting government forces in Swat, Bajaur, and Mohmand. Last year, Baitullah Mehsud, the commander of the Pakistani Taliban, had threatened to wage "jihad" and turn the provinces of Sindh and Punjab "into a furnace" if the operations in northwestern Pakistan did not cease.

While no group has yet been identified as having caused the attack, the Laskhar-e-Jhangvi probably was behind it. The Lashkar-e-Jhangvi (LeJ or Army of Jhangvi) was formed in 1996 after splitting with the Sipah-e-Sahaba, a radical Sunni group behind sectarian attacks against Shia throughout Pakistan. The Lashkar-e-Jhangvi expanded its activities to include terror attacks against the Pakistani state. After Sept. 11, 2001, LeJ was one of two Pakistani terror groups banned by the Musharraf regime.

Al Qaeda, the Taliban, and other Pakistani terror groups have used the Laskhar-e-Jhangvi to execute operations inside Pakistan for years, a senior US intelligence official told The Long War Journal in September 2008. "Harkat-ul-Jihad-al-Islami, Laskhar-e-Jhangvi, and other Pakistani terror groups merged with al Qaeda years ago," the official said. "The group acts as street muscle" for al Qaeda.

The size of the LeJ is unknown, but it is believed to have hundreds of members dispersed in small cells throughout Pakistan. The group maintains camps in South Waziristan, under the protection of Baitullah Mehsud.

After a string of attacks during the winter and spring of 2006, Pakistani police began to openly admit that the LeJ had begun forging close ties with al Qaeda and the Taliban. One of the most most high-profile LeJ attacks after Sept. 11 was the March 3, 2006, bombing outside the US Consulate in Karachi. A US diplomat was killed in the suicide car bombing.

The Lashkar-e-Jhangvi was also behind the deadly Sept. 20, 2008, bombing at the Marriott hotel in Islamabad that killed more than 50 Pakistanis and foreigners, wounded more than 270, and destroyed the once-popular hotel.