At least 10 train carriages were torched in what Metrorail management believes to be an arson attack over the weekend.
Metrorail's Richard Walker says the evidence points to deliberate sabotage of their infrastructure on Saturday evening.
The preliminary information clearly demonstrates that the trains were set alight purposefully... It was a very orchestrated and planned attack of our assets... the fire was accelerated and assisted.— Richard Walker, regional manager at Metrorail
According to Walker, the police are busy with an investigation and are confident that the suspects will be brought to book.
He says CCTV footage at the train platforms will form part of the probe, but refused to speculate about the involvement of any group or organisation.
Walker has warned commuters to expect major delays and cancellations on the Northern Line as a result of the damage.
Listen to the full conversation from CapeTalk's Breakfast with Kieno Kammies: