A Taliban suicide bomb packed with ball bearings tore through a Pakistani hospital Monday and killed at least 70 people, as witnesses described tearful staff rushing towards the smoking blast site to help the wounded.

A Taliban suicide bomb packed with ball bearings tore through a Pakistani hospital Monday and killed at least 70 people, as witnesses described tearful staff rushing towards the smoking blast site to help the wounded.

The bomber struck a crowd of some 200 people gathered at the Civil Hospital in the Balochistan provincial capital Quetta after the fatal shooting of a senior local lawyer earlier in the day. More than 100 were wounded, officials said.

Video footage showed bodies strewn on the ground, some still smoking, among pools of blood and shattered glass as shocked survivors cried and comforted one another.

Many of the victims were clad in the black suits and ties traditionally worn by Pakistani lawyers.

Police confirmed the attack was a suicide blast.

"The bomber had strapped some eight kilograms (18 pounds) of explosives packed with ball bearings and shrapnel on his body," bomb disposal unit chief Abdul Razzaq told AFP.

A faction of the Pakistani Taliban, Jamaat-ul-Ahrar, claimed responsibility for the attack in an email to journalists.

Jamaat-ul-Ahrar has also said it was behind the deadliest attack in Pakistan so far this year, a bombing in a crowded Lahore park that killed 75 people on Easter Sunday.

A spokesman vowed more attacks "until the imposition of an Islamic system in Pakistan".

"The death toll has risen to 70 and there are 112 injured," the head of the provincial health department, Dr Masood Nausherwani, told reporters.

Officials said mobile phone jammers had been activated around hospitals in the area -- a regular precaution after an attack -- making it hard to contact officers on the ground to get updated information.