According to media reports, a gas cylinder carried by a passenger exploded, leaving several dead and injured.
The train, Tezgam, was on its way to Rawalpindi from Karachi when the fire broke out, destroying three of the train's carriages at Liaquatpur near Rahim Yar Khan in Punjab province, the Geo News reported.
Many died after leaping from the moving train, trying to escape the flames. Railways Minister Sheikh Rashid said that the persons responsbile were part of the Tableegi Jamaat, a religious entity, who were going to Lahore to participate in their annual congregation at Raiwind. Numerous bodies were charred beyond recognition.
Rescue workers shift the bodies of the victims after a fire engulfed a passenger train near Rahim Yar Khan, Pakistan, 31 October 2019. He said that a short circuit had caused the bogies to catch fire.
"The Railway Minister has admitted his administration's failure for not checking the cylinders the passengers brought with them". At least 54 passengers were travelling in the business class carriage.
A hospital in Rahim Yar Khan was overwhelmed with victims and had to turn some patients away.
"I jumped out of the train to save my life. My brother and I managed to jump off the train, but my mother and sister couldn't", PTI quoted Iftikhar Ahmed, an injured person, as saying.
Survivors have spoken of horrific scenes including fellow passengers jumping to their deaths from the train as flames filled the carriages.
A raging fire swept through a train in Pakistan's eastern Punjab Province on Thursday killing 74 people and survivors said afterward it took almost 20 minutes for the train to stop amid contradictory reports about the condition of the train's brakes.
In a video message, Railways Minister Rashid announced that a compensation of Rs1.5 million will be paid to the heirs of the deceased while Rs500,000 will be provided to those who are injured.
"It was our negligence that they were allowed to board with gas cylinders", Rasheed added.
PML-N President Shehbaz Sharif said he was "heartbroken at such a massive train tragedy" and offered condolences to the bereaved families.
Pakistan prime minister Imran Khan tweeted that he is deeply saddened by the bad tragedy and offered condolences for the families of victims and prayers for the injured. Khan also ordered an urgent investigation into the incident.
Firefighters were deployed to the site, and military helicopters were flown in to airlift the injured. Rescue operations are underway.
Numerous passengers were religious pilgrims travelling to a congregation in the eastern city of Lahore.
CEO Pakistan Railways Aijaz Ahmad said the train schedule would not be affected by this incident.
Pakistan has a history of deadly train accidents stemming from poor railway infrastructure.
Kaleem Ullah, an official with the district emergency services, says another 43 people are injured, with 11 still in critical condition following the blaze on the train traveling in eastern Punjab province on Thursday morning.
Last year, nine bogies of the Peshawar-bound Khushal Khan Khattak Express from Karachi derailed near Attock.