A collision involving two passenger trains in southern Pakistan has killed at least 40 people and injured dozens.
A train travelling in Sindh province derailed and landed on another track, officials said. A second train packed with passengers then collided with it and overturned.
Rescue teams took the injured to nearby hospitals and it is thought that several are in a critical condition.
Pakistan has seen a string of deadly train accidents over the past years.
Between 2013 and 2019, 150 people died in such incidents, according to local media reports.
The accident in Ghotki district happened early on Monday when the Millat Express coming from Karachi derailed, falling on to another track. It is not clear what caused the derailment.
The Sir Syed Express coming from Rawalpindi collided with it and overturned.
A senior official in the Ghotki district, Usman Abdullah, told Reuters news agency it was hard to know how many people were still trapped in the train.
“There are about six to eight bogies [carriages] that are totally smashed… there is a sleeper train, AC [air conditioned] class, as well as economy class, in which there were between 47 to 50 people on this side and around 50 to 60 people on the other train,” he said.
Prime Minister Imran Khan said he was “shocked” by the accident and promised a full inquiry.
Minister for Information Fawad Chaudhry said that more than 100 people were injured, and it was feared the death toll would rise.
“Unfortunately, for a long time, our railway system and other departments have been deprived of the finances that should have been invested in them,” he said. “As a result, we are witnessing a deterioration in these departments.”
A passenger on board one of the trains told Agence France-Presse that he felt lucky to have survived.
“It happened at 03:30,” he said. “We were asleep when we felt jerks. Luggage began to fall down. Thank God we stayed safe.”
Hospitals in the area have been put on emergency alert to deal with the casualties, and helpline centres have been set up for passengers.
Railway accidents are not uncommon in Pakistan, often caused by derailment and collisions at unmanned railway crossings.
The railways are an essential mode of travel, especially among middle and lower income groups, with tracks spanning the length and breadth of Pakistan.
However, carriages are often overcrowded and many of the trains are in poor condition.
Last July 21 people were killed near Sheikhupura, Punjab province, when a train travelling from Karachi to Lahore hit a van carrying Sikh pilgrims.
In October 2019 a fire caused by a gas cylinder killed more than 70 passengers on a train travelling from Karachi to Rawalpindi, and another 20 people were killed in a train crash a few months earlier, in July 2019.
Data from Pakistan Railways shows there were 757 train accidents between 2012 and 2017 – an average of about 125 incidents a year.
According to the authorities, the three major causes of train accidents in Pakistan are lack of track maintenance, signal issues and older engines.