Two trains have collided in southern Pakistan leaving at least 35 passengers dead, authorities said.
Between 15 and 20 passengers are still trapped in the wreckage of one train, said police chief Umar Tufail.
The collision occurred in the Ghotki district in Sindh province just before dawn.
Authorities are trying to arrange heavy machinery to rescue those people who are crying for help, Mr Tufail added.
The Millat Express derailed and the Sir Syed Express train hit it soon afterwards, said Usman Abdullah, a deputy commissioner in Ghotki.
It was not immediately clear what caused the derailment and the subsequent collision.
‘We are not sure about the cause of the accident’
"Right now the challenge for us is to quickly rescue those passengers who are still trapped in the wreckage," he said.
Azam Swati, minister for railways, told the Associated Press that so far 35 people had died and dozens of others were injured.
"I am on my way to the Ghotki district where the tragic train accident happened today," he said.
Mr Swati said engineers and experts were trying to determine what caused the collision.
He said all aspects will be examined, including the possibility of sabotage.
"We are not sure about the cause of the train accident at this stage," he said.
Around 1,100 passenger on board two trains
According to railway officials, about 1,100 passengers were on board the two trains, and arrangements were being made to assist the survivors.
A military statement said that troops were participating in the relief and rescue at the scene.
It said military doctors and ambulances were also dispatched from a nearby city and a team of military engineers was sent to Ghotki by helicopter.
According to local media, some of the passengers were travelling on the Millat Express train to attend a wedding party but it was unclear whether they were among the dead or injured.
Pakistan prime minister orders probe into crash
Pakistan's prime minister expressed his deep sorrow over the tragedy.
Imran Khan said on Twitter that he had asked the railway minister to supervise the rescue work and also ordered a probe into the crash.
Officials at Pakistan railways said they had ordered an investigation and rescue work was still in progress.
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