A Pakistani Taliban faction and the Islamic State of Iraq and the Levant (ISIL) have both claimed responsibility for a suicide attack at a hospital in Pakistan's Quetta that killed at least 70 people.

Monday's attack targeted a group of mourning lawyers, who had gathered at the emergency department of the hospital to accompany the body of a murdered colleague.

"The Tehreek-e-Taliban Pakistan Jamaat-ur-Ahrar takes responsibility for this attack, and pledges to continue carrying out such attacks. We will release a video report on this soon," the group's spokesman Ehsanullah Ehsan said in an email.

ISIL, which is also known as ISIS, also claimed responsibility for the attack.

"A martyr from the Islamic State [of Iraq and the Levant] detonated his explosive belt at a gathering of justice ministry employees and Pakistani policemen in the city of Quetta," the armed group's Amaq website said.

The blast happened at the gate of the emergency room in the morning.

The lawyers were at the unit because earlier in the day armed men, who are still unidentified, had shot Bilal Anwar Kasi, reports said.

Kasi, who later died from his injuries, was the former president of the Balochistan Bar Association. He had been on his way to work when he was attacked.

Many of the dead appeared to be lawyers, wearing black suits and ties.

Balochistan Home Minister Sarfraz Bugti said: "The blast occurred after a number of lawyers and some journalists had gathered at the hospital following the death of Bilal Anwar Kasi, the president of the Balochistan Bar Association, in a separate shooting incident early this morning."

One cannot even imagine anyone stooping as low as to target a hospital ... Only those bereft of humanity can do that ... — Shehbaz Sharif (@CMShehbaz) August 8, 2016

Several people were wounded as they rushed to leave the hospital.

Pakistani media said that journalists were among the victims, with at least two cameramen killed. One cameraman was named by local media as Aaj TV's Shehzad Khan.

The other was Mehmood Khan of Dawn News, who had in the past worked for Al Jazeera. His colleague Sumaira Jajja wrote on Twitter that Khan, a father of seven children, started out as a security guard before joining Dawn as an officer worker to then become a cameraman. He had planned to do a master's degree in journalism.

Condemnable cowardly terrorists strike Quetta targeting bar president then civil hospital. Even in war hospitals not delib targeted. — Imran Khan (@ImranKhanPTI) August 8, 2016

Balochistan, which borders Iran and Afghanistan, has oil and gas resources and is afflicted by fighting, violence between Sunni and Shia Muslims, and a separatist rebellion.

"The attack took place at the main gate to the emergency area," said Al Jazeera's Kamal Hyder, reporting from Islamabad.

"Importantly, this happened after the president of the Quetta bar was gunned down," he said. "There are big questions after this security lapse. There is a very heavy death toll and most killed today are people belonging to the legal fraternity."

Hyder said an attack took place at the same hospital in 2010.