The suicide and car bomb attacks Thursday night struck two different sections of the capital of resource-rich Baluchistan province, which has been plagued by sectarian violence and a separatist rebellion.
CNN, quoting authorities, said the blasts killed at least 93 people and wounded 169.
Quetta, in southwest Pakistan, has a large population of minority Shiite Muslims in the Sunni majority country.
Dawn, Pakistan's leading English daily, reported most of the deaths were at a snooker club in the Alamdar Road area.
The report said the attacks there came hours after 12 people died in an explosion near a vehicle belonging to the Pakistani paramilitary force at the Bacha Khan Chowk shopping area. The dead there included a cameraman and a reporter of a private television news channel and some police personnel, while another 10 were injured, Dawn said, quoting police.
A majority of the people killed in the blasts in the snooker club at Alamdar Road belonged to the Hazara Shiite community, Dawn reported.
Dawn said the banned Lashkar-i-Jhangvi claimed responsibility for the attacks.
A police official said the death toll in the blasts could go up because of the serious nature of the injuries of some of the injured people.
There were two attacks at the snooker club, one believed to be by a suicide bomber, when the facility was crowded with players.
"A man entered the snooker club and a powerful blast took place," police sources told Dawn.
That was followed minutes later by a car bombing outside the club as people were busy assisting police and rescue workers involved in the first blast, Dawn said. The second blast killed at least five policemen, two rescue workers, and three journalists, the report said, quoting authorities and eyewitnesses.
"The building which housed the snooker club was destroyed completely, while over 50 shops and nearby houses were badly damaged," one eyewitness told Dawn.
"Bodies littered a large area," another eyewitness told Dawn.
The Bacha Khan Blast occurred when the area was crowded with shoppers, a shop owner told Dawn.
"The target of the bomb blast was the vehicle carrying FC (paramilitary) men and a check post in the area," a police official told reporters.
CNN quoted officials that children were among those killed in the explosions but gave no other details.
CNN quoted police spokesman Wazir Khan Nasir as saying at least 45 people were injured in the Bacha Khan area blast.
The office of Pakistani Prime Minister Raja Pervez Ashraf said the prime minister, in condemning the attacks, reiterated the government's resolve "to stamp out the menace of militancy and terrorism from the country in its all shapes and manifestations."