MASTUNG: Nineteen people were killed and 25 others were injured after three passenger buses were struck by an explosion in Mastung's Dringarh area early on Sunday, DawnNews reported.

The remotely-triggered bomb hit a convoy of three buses in Mastung district and set one of them ablaze, said Tufail Baluch, a senior government official in the district.

“At least 19 people have been killed and 25 injured. All of them were Shia pilgrims,” he told AFP, adding most of those killed were burnt to death.

“The bomb was planted in a car. The condition of some of the injured is critical,” Baluch said.

Some 180 Shia pilgrims were on their way to Iran in the buses when the bomb ripped through one of them, said Akbar Hussain Durrani, a senior government official in Quetta, the capital of Balochistan province.

One of the buses caught fire as a result of the intensive explosion and was completely destroyed whereas the two other buses also suffered partial damage.

Pakistan's President Asif Ali Zardari condemned the incident and offered condolences to the relatives of those who died in the attack.

There was no immediate claim of responsibility for the attack.

The injured were shifted to District Hospital Mastung.

Security forces cordoned off the area as investigations into the blast went underway.

Shias regularly travel to Iran's Taftan city to perform pilgrimage.