QUETTA: A suicide bomber in Pakistan killed at least 63 people and wounded dozens more in an attack on mourners gathered at a hospital in Quetta, according to officials in the violence-plagued southwestern province of Baluchistan.

The bomber struck as more than 100 mourners, mostly lawyers and journalists, crowded into the emergency department to accompany the body of a prominent lawyer who had been shot and killed in the city earlier in the day, Faridullah, a journalist who was among the wounded, told Reuters.

Abdul Rehman Miankhel, a senior official at the government-run Civil Hospital, where the explosion occurred, told reporters that at least 63 people had been killed, with more than 50 wounded, as the casualty toll spiked from initial estimates.

"There are many wounded, so the death toll could rise," said Rehmat Saleh Baloch, the provincial health minister.

Television footage showed scenes of chaos, with panicked people fleeing through debris as smoke filled the hospital corridors.

The motive behind the attack was unclear and no group had yet claimed responsibility, but several lawyers have been targeted during a recent spate of killings in Quetta.

The latest victim, Bilal Anwar Kasi, was shot and killed while on his way to the city's main court complex, senior police official Nadeem Shah told Reuters. He was the president of Baluchistan Bar Association.

The subsequent suicide attack appeared to target his mourners, Anwar ul Haq Kakar, a spokesman for the Baluchistan government, said.

"It seems it was a pre-planned attack," he said.

Police cordoned off the hospital following the blast.

Aside from a long-running separatist insurgency, and sectarian tensions, Baluchistan also suffers from rising crime.

In January, a suicide bomber killed 15 people outside a polio eradication centre in an attack claimed by both the Pakistani Taliban and Jundullah, another Islamist militant group that has pledged allegience to Islamic State in the Middle East.

Quetta has also long been regarded as a base for the Afghan Taliban, whose leadership has regularly held meetings there in the past.

In May, Afghan Taliban leader Mullah Akhtar Mansour was killed by a U.S. drone strike while travelling to Quetta from the Pakistan-Iran border.