A Pakistan Railways train carrying around 300 passengers from the provincial capital Quetta to the northern city of Rawalpindi was derailed on Tuesday, though the cause remains unknown.
Officials said that three more people succumbed to their injuries overnight.
“The death toll has risen to 19 now. A total of 96 people are being treated in hospitals and around a dozen are still critical,” Akbar Hussain Durrani, home secretary of Baluchistan province, told AFP.
Meanwhile an official from Pakistan Railways said experts visited the accident site on Tuesday morning and an inquiry panel is likely to be set up to ascertain the causes.
Train accidents are common in Pakistan, which inherited thousands of miles (kilometres) of track and trains from former colonial power, Britain.
The railways have seen decades of decline due to corruption, mismanagement and lack of investment.
In July, at least 17 people were killed when a special military train fell into a canal after a bridge partially collapsed.