The bomb -- apparently detonated by remote control -- injured at least 175 people in a crowded market in Qetta, including a number of women and children, the Los Angeles Times said.
"The death toll may rise," senior police officer Wazir Khan Nasir told DAWN.com. "It was a remote-controlled bomb."
The explosion occurred along a busy street near a school in a section of town with a large population of ethnic Hazaras, a group tied to the Shiite branch of Islam.
"It was a sectarian attack," the officer said. "the [Shite]community was the target."
DAWN.com said the explosion brought scores of police and troops to the area, and Hazara leaders issued calls for a strike Sunday to protest the attack.