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.
Burned school bags and books were strewn around.
"The explosion was caused by an improvised explosive device fitted to a motorcycle," said Wazir Khan Nasir, deputy inspector general of police in Quetta.
Pakistani law enforcement officials say Lashkar-e-Jhangvi has become a formidable force.
Last month the group said it carried out a bombing in Quetta that killed nearly 100 people, one of Pakistan's worst sectarian attacks. Thousands of Shi'ites protested in several cities after that attack.
Pakistani intelligence officials say extremist groups, led by Lashkar-e-Jhangvi, have escalated their bombings and shootings of Shi'ites to trigger violence that would pave the way for a Sunni theocracy in U.S.-allied Pakistan.
The growing sectarian violence has hurt the credibility of the government, which has already faced criticism ahead of elections due in May for its inability to tackle corruption and economic stagnation.
