A Pakistan Taliban faction said it carried out a bomb blast that killed at least 70 people at a hospital in the city of Quetta.
Dozens of people were injured in the attack, which happened at the entrance to the emergency department where the body of a prominent lawyer shot dead earlier on Monday was being brought.
The casualties included lawyers and journalists accompanying the body of Bilal Anwar Kasi.
Gunfire followed the explosion, but it was not clear who the attackers were.
Pakistan police said they suspected the bomb was detonated by a suicide attacker.
There have been a number of targeted killings in Quetta linked to a separatist insurgency, as well as sectarian tensions and crime.
Those killed in recent weeks have included several lawyers.
Mr Kasi, who was president of the Balochistan Bar Association, had been shot while on his way to the main court complex in Quetta, local news outlet Geo TV reported.
Pakistan Prime Minister Nawaz Sharif condemned the attacks.
"No-one will be allowed to disturb the peace of the province," he said.
"The people, policy and security forces in Balochistan have given sacrifices for the country."
Balochistan province chief minister Sanaullah Zehri said those injured should be given the best medical treatment and facilities available.
Mr Kasi had strongly condemned the attacks and local media said he had announced a two-day boycott of court sessions in protest at the killing of a colleague last week.
Those killed in the hospital attack were said to include Baz Muhammad Kakar, a predecessor of Mr Kasi as provincial bar president, 17 other lawyers and Shahzad Khan, a cameraman for Aaj TV.
Facebook has activated its safety check feature for Quetta, allowing users to mark themselves or others as being safe.