At least 35 passengers were killed in Pakistan as two trains collided on early Monday. 

Authorities say that the rescuers and locals are still working to pull out the injured and the dead who are trapped inside the train. the Police Chief of the local district said that between 15 to 20 passengers are believed to be still trapped inside the train.

The incident happened in the Ghotki district of southern Pakistan.

The clash occurred when the train of Sir Syed Express hit a derailed train of Milliat Express. It has not been clear what caused the derailment and the subsequent collision, local police said.

“Right now the challenge for us is to quickly rescue those passengers who are still trapped in the wreckage,” he said.

Pakistan's Minister for Railways, Azam Swati said 35 people died in the accident and dozens have been injured. The death toll could rise as the rescue operation is underway.