A Transnet goods train derailed between Tygerberg and Bellville railway stations in Cape Town on Monday, severely delaying commuter services.
"Under current circumstances, delays could exceed 120 minutes," Metrorail spokesperson Riana Scott said.
Scott said the derailment occurred around 08:30 and the cause was unclear. Transnet's media spokesperson was not immediately available to provide further details.
However, the known impact for people travelling on that line is that services are severely delayed.
Until Transnet provided a prognosis on clearing the derailment site, Metrorail trains were being held in Parow and Bellville until further notice, Scott said.
Northern commuters were advised to use the Monte Vista service and to check social media channels, call 0800 65 64 63, or listen to announcements at stations for updates on service recovery.
Sonja Carstens, spokesperson for the United National Transport Union (UNTU), said information about the derailment was sketchy.
"The information we have received to date is that no one has been injured," she added.