Islamabad , Pakistan ( CNN ) -- A blast targeting a bus filled with Shiite religious observers in Karachi killed at least 12 people and another explosion in front of a hospital where attack victims were being treated killed six more Friday , a government official said . Motorcycles were used in both assaults , police said , and they came during the Shiite observance of Arbaeen , a commemoration that takes place 40 days after the anniversary of Iman Hussein 's death , which is also known as Ashura . Sindh provincial health minister , Dr. Saghir Ahmed said that along with the 12 dead , 30 people were injured in the first blast . The second blast happened in front of the emergency room at Jinnah Hospital , where doctors treated people from the first attack and people on stretchers were waiting to be taken in to the crowded facility . Along with the six slain , five people were wounded . The last deadly blast in Karachi took place late December during Ashura , when more than 40 people were killed .
Two bomb blasts kill Two in Pakistan ; motorcycles used in both attacks . Two killed in the first explosion which targeted Shiite religious observers on a bus . 6 killed in second attack which occurred outside a hospital treating victims of first blast . Attacks came during the Shiite observance of CNN .