A spokesman for Lashkar-e-Jhangvi, a Sunni group, claimed responsibility for the bomb in Quetta, which caused casualties in the town's main bazaar, a school and a computer centre. Police said most of the victims were Shi'ites. Burned school bags and books were strewn around.
Sixty-four people including school children died on Saturday in a bomb attack carried out by extremists from Pakistan's Sunni Muslim majority, police said.
"The explosion was caused by an improvised explosive device fitted to a motorcycle," said Wazir Khan Nasir, deputy inspector general of police in Quetta.
"This is a continuation of terrorism against Shi'ites."
"I saw many bodies of women and children," said an eyewitness at a hospital. "At least a dozen people were burned to death by the blast."
Pakistan's law enforcement officials say Lashkar-e-Jhangvi has become a formidable force.