
RapidKL said on Twitter that the maintenance car had derailed between the Jelatek and Dato Keramat stations.
This caused a temporary halt in service from KLCC to Gombak, with eight buses deployed to ferry passengers between the two stations.
Further updates said single-direction movement was regained from Gombak to Pasar Seni, with trains coming every four to five minutes.
More recent updates from RapidKL said trains are now moving normally from Putra Heights to Gombak.
However, trains from Gombak to Setiawangsa will be diverted to the next track before proceeding to Putra Heights.
RapidKL said commuters will get full refunds for their fares while Touch ‘n’ Go users can obtain refund vouchers from customer service counters.