Pakistan mourners gather at the funeral of victims of a bus accident in Karachi. (Agence France-Presse)
Pakistani police said on Wednesday they will investigate government departments over a bus crash that killed 57 people, blaming the poor condition of the road for the accident.
The bus smashed into a goods truck loaded with coal near the city of Khairpur, 450 kilometres (300 miles) north of Karachi, on Tuesday. There were 18 children among the dead.
District police chief Nasir Aftab told AFP the initial investigation found the road was in poor condition and had no warning signs to alert drivers to the danger.
"A first information report (FIR) for becoming cause of death has been registered and the concerned departments will be investigated for the bus accident," Mr Aftab said.
He said it was the first time a government department would be investigated for a road accident in Pakistan.
Motorway police official Faisal Chachar said that a 61-kilometre (38-mile) stretch of the road was in poor condition, having developed a significant furrow in its surface.
A senior motorway police officer told AFP on Tuesday the bus driver, carrying Pashtun families from northwestern Swat valley to Karachi, had lost control after hitting the rut in the road.
Pakistan has an appalling record of fatal traffic accidents due to poor roads, badly maintained vehicles and reckless driving. Crashes killing dozens of people are not uncommon.
In April a bus smashed into a tractor-trailer in a high-speed collision in Sindh, killing 42 people, while in March a horrific crash between two buses and a petrol tanker left 35 dead, with many burned alive when the fuel ignited.