Two passenger trains collided in southern Pakistan Monday, killing at least 35 people and wounding dozens of others, per AP.

Details: Up to 20 people were trapped in the Millat Express' wreckage after the collision with the Sir Syed Express in Ghotki district in Sindh province, just over 270 miles north of Karachi, AP reports.

• The Millat Express had derailed for an as-yet unknown reason and the Sir Syed Express struck the train soon after.

What they're saying: Prime Minister Imran Khan tweeted that he has asked Railways Minister Azam Khan Swati to go to the crash scene and oversee rescue operations, adding he has ordered a "comprehensive investigation into railway safety fault lines."

• Swati said authorities were also investigating the cause of the collision, but it's "too early to say whether the accident was due to sabotage or due to the dilapidated condition of the train track," according to the New York Times.

The big picture: Pakistan's railways have a poor safety record and the system is dogged by"corruption and mismanagement," per the NYT.

• Khan pledged to improve the badly maintained, aging system when he was elected in 2018, but train accidents have continued under his government — notably in 2019 when a train caught fire and killed over 70 people, the NYT notes.

Editor's note: This article has been updated with new details throughout.