At least 63 people were killed and around 100 injured in a head-on collision between two passenger trains in southern Pakistan on Monday morning, local media reported citing authorities. 

Local authorities have issued two lists of the dead that included 12 unidentified people from the accident, according to the report. 

According to the reports, the accident took place in the area between Raiti and Obaro railway stations in Ghotki District of Sindh Province. Following the collision, several coaches of the two trains derailed and turned over. 

Rescue teams rushed to the site and shifted bodies and the injured to nearby hospitals. The military deployed troops, engineers and helicopters to assist.

About 1,100 passengers were aboard the two trains, railway officials said.

The toll was expected to increase as there were still mangled train compartments that rescuers had not been able to access hours after the accident, Umar Tufail, a senior district police official, told local television channel Geo News. 

The accident occurred between the Millat Express, which was heading towards the eastern city of Sargodha from the southern port city of Karachi, and the Sir Syed Express, which was going to Karachi from eastern city of Rawalpindi. 

Aijaz Ahmed, the driver of the Sir Syed Express, told the station that on seeing the derailed train, he tried his best to avoid the crash by braking but failed. 

It wasn't immediately clear what caused the collision.