40 killed in Pak in attacks on Shia pilgrims, soldiers
Explosives planted in a car parked by the roadside were detonated by remote control when the bus was passing through Mastung district of Baluchistan province, Deputy Commissioner Tufail Baloch told reporters.
"Nineteen people were killed and 25 more injured," he said.
Other officials said the wounded, many of them with burn injuries, were taken to two hospitals in the provincial capital of Quetta.
Officials of the bomb disposal squad said an estimated 80 kg of explosives were used in the attack.
No group claimed responsibility for the incident though the banned Lashkar-e-Jhangvi has been blamed for earlier attacks on Shias in Balochistan.
The vehicle that was targeted was part of a convoy of three buses carrying Shia pilgrims from Lahore, Jhang and Multan in Punjab province, to neighbouring Iran.
The buses were headed for the Taftan border crossing.
Baloch said the buses had been provided an escort in view of earlier attacks on Shia pilgrims.
The route taken by the buses is usually cleared in advance but the attack occurred near a market where several vehicles were parked by the roadside, he said.
The explosion triggered a fire in the bus.
Witnesses said several persons were burnt alive.
Footage on television showed that the bus was reduced to smouldering metal.
Rescue workers were seen removing charred