London, June 7: Two passenger trains have collided in southern Pakistan, killing at least 30 people and injuring dozens more.

Officials said that one train traveling in the Sindh province had derailed and landed on another track. 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 critical condition.

Pakistan has over the past years seen a string of deadly train accidents. A senior official in the Ghotki district was quoted as saying that eight carriages were destroyed and that conditions were making it hard to rescue trapped passengers.

Prime Minister Imran Khan said he was "shocked" by the accident and promised a full inquiry.

Footage from the site shows the wreckage of several carriages lying on their side. It is not clear what caused the derailment.

Early on Monday, several people were still trapped in the wreckage. News agency AFP quoted a railway spokesperson as saying: "The site is far and that's why we are facing some trouble in the rescue work."

Hospitals in the area have been put on emergency alert to deal with the casualties.

The accident happened early on Monday when the Millat Express coming from Karachi derailed, falling onto another track. The Sir Syed Express coming from Rawalpindi collided with it and overturned.

Local media have cited officials as saying that a relief train has been dispatched to the crash site while helpline centers have been set up for passengers.

Railway accidents are not uncommon in Pakistan, often caused by derailment and collisions at unmanned railway crossings.

Train travel is an extremely popular mode of travel in Pakistan, especially among middle and lower-income groups, with tracks spanning the length and breadth of the country.

However, carriages are often overcrowded and many of the trains are in poor condition. According to the authorities, the three major causes of train accidents in Pakistan are lack of track maintenance, signal issues, and older engines.

Casualty figures are often high because trains are packed with far greater numbers of passengers than they were designed for.