KARACHI, Pakistan – Beating their chests with hands, thousands of minority Shi'ite Muslims attended a mass funeral Saturday for those killed in a pair of bombings in Pakistan's largest city. At least 31 people died and 170 others were wounded in Karachi on Friday when suspected Sunni militants targeted a bus carrying Shi'ite worshippers and then attacked a major hospital treating victims of the first bomb, said government spokesman Jamil Soomro. Karachi has a history of religious violence between Shi'ite and Sunni Muslims, and the city has been tense in recent weeks due to clashes between rival political parties that have left dozens dead. Paramilitary spokesman Maj. Aurang Zeb said security forces were on maximum alert at the funeral in the Malir area of the southern port city. Many businesses were observing a strike over the attacks. Witnesses said about 7,000 mourners attended the funeral. Although no group claimed responsibility, Pakistan is home to Sunni extremist groups with a history of attacking Shi'ites. In late December, 44 people died when a bomb ripped through a Shi'ite procession in the city to mark the anniversary of the death of revered Shi'ite figure Imam Hussein.