Pakistani militants have struck at the heart of the country's legal profession, killing a prominent lawyer and then bombing the hospital where dozens of others had gathered to mourn.
The twin attacks killed at least 70 people, most of them lawyers, authorities said.
A breakaway faction of the Pakistani Taliban claimed the attacks in Quetta, the capital of restive Baluchistan province, which also wounded dozens of others.
In a statement, Ahsanullah Ahsan, spokesman for the Jamaat-ul-Ahrar militant group, said its fighters killed Bilal Kasi, the president of the Baluchistan Bar Association, then as dozens of lawyers gathered at the government-run Civil Hospital, a suicide bomber targeted the mourners.
Jamaat-ul-Ahrar has been behind several attacks in Pakistan in recent years, including a bombing on Easter Sunday in a park in the eastern city of Lahore that killed at least 70 people.
Witnesses described horrifying scenes of bodies scattered on the ground and the wounded screaming for help.
A senior police official said Mr Kasi was killed by gunmen as he was on his way to his office. He was among the most outspoken lawyers in Baluchistan and was popular for campaigning for improvements in the legal community.
"It was a suicide attack," said the police official, Zahoor Ahmed Afridi.
He said remains of the attacker had been found and authorities were trying to identify them.
More than 90 people were wounded in the explosion, according to Civil Hospital director Abdul Rehman. Two journalists working for Pakistani news channels were among those killed in the attack, according to Shahzada Zulfiqar, the president of the Quetta Press Club.
Ali Zafar, the head of the country's main lawyers' association, condemned the blast as "an attack on justice".
He said lawyers would observe three days of mourning and would not appear in court in solidarity with their colleagues and others killed in the attack.
Prime minister Nawaz Sharif strongly condemned the blast and expressed his "deep grief and anguish over the loss of precious human lives".
"No one will be allowed to disturb the peace in the province that has been restored thanks to the countless sacrifices by the security forces, police and the people of Baluchistan," he said in a statement.
He urged local authorities to maintain vigilance and beef up security in Quetta.
The prime minister later travelled to Quetta to meet the wounded and assess the situation. At a high-level meeting of security officials he ordered stern action against terrorists.
"Terrorists are using innovating measures by hitting soft targets and one must respond in an advanced, co-ordinated way," he said in a statement.
Quetta and the rest of Baluchistan province, which borders Afghanistan and Iran, have long been plagued by insurgency.
Several ethnic Baluch separatist groups operate in the resource-rich province, as well as al Qaida, the Pakistani Taliban and other militant groups.
Lawyers have been targeted in the past by militants in various parts of Pakistan.
They are considered an important part of civil society and emerged as powerful actors in 2007, when then-president Pervez Musharraf fired the chief justice, Iftikhar Mohammad Chaudhry.
Lawyers launched nationwide protests to pressure Mr Musharraf to reinstate Mr Chaudhry.
Later, political parties joined the campaign and Mr Musharraf was ultimately forced to resign in 2008 and Mr Chaudhry was reinstated.