Cape Town station's platforms 15 and 16 will be closed until further notice after two motor coaches and five passenger coaches went up in flames there on Saturday, Metrorail said.
The coaches that were burnt out were part of the northern fleet and would put services at the station under strain.
A loss of R30m and damage to 160 meters of overhead electrical wire was a result of the fire.
Commuters were warned to expect cancellations in the slots usually served by these two train-sets, platform changes and revised arrival/departure times at Cape Town Station as trains using platforms 15 and 16 are slotted into alternative platforms.
"Loyal commuters reliant on rail transport have once again been dealt a blow," said regional manager Richard Walker.
Forensic teams had searched for clues before mop-up began.
Metrorail was working with the police to investigate the incident and encouraged anyone with information or footage of the event to report it to the police.
"While the reasons behind the fire are still sketchy, it is reported that one train arrived at the station, at platform 15, with one of the coaches already on fire," Prasa spokesperson Nana Zenani said earlier in a statement.She added, however, that "other reports suggest that the train was set alight when passengers got off the train when it arrived at the station".
There is a reward of R25 000 for information leading to a successful conviction of the perpetrators.