A suicide truck bomb killed more than 70 people Tuesday . The attack occurred in the town of Mazar-i-Sharif, a stronghold for Taliban militants and their allies who have been fighting U.S.-led forces since 2001. Al-Shabaab claimed responsibility for the blast .
A suicide truck bomb killed more than 70 people Tuesday . Somalia 's president visits hospitals and bombing scene , calls for three days of mourning . Al-Shabaab claimed responsibility for the blast .