A multi-vehicle collision involving two trucks and two passenger buses on a coastal highway in southwestern Pakistan early on Saturday killed 35 people and injured 20 passengers, police said.
The accident took place in Baluchistan province, near Gadani, a coastal town known for its shipbreaking industry some 600 kilometres (370 miles) south of Quetta, the provincial capital.
A bus bound for the port city of Karachi first collided head-on with a truck coming from the opposite direction, said Ahmed Nawaz, the area's police chief.
Nawaz said the second bus and truck then piled up onto the two vehicles and all caught fire, mostly because the buses were also smuggling Iranian gasoline and diesel-filled canisters on board.
He said 25 people were reported to have died at the scene while 30 injured victims were taken out of the destroyed and burned buses.
Most of the victims, including women and children, were severely burned and were transported to Karachi. Ten of the injured died on the way, raising the death toll to 35, said Nawaz.
The inter-city buses operating across Baluchistan, which borders Iran, often carry canisters of smuggled Iranian gasoline and diesel.
"It is routine, we are compelled to do this, even though it is illegal and dangerous," said Mohammad Hasan Lehri, who works as a bus driver on the Quetta-Karachi route.
Lehri said thousands of people are involved in the illegal trade and everyone gets a share of the profits, a veiled reference to policemen who may be on the take.
Bad road infrastructure and poor driving and implementation of traffic laws and regulations often cause deadly accidents in Pakistan.