The train derailed near 48th Avenue at 10:54 a.m., Muni spokesman Judson True said. There were no reports of injuries to passengers or Muni personnel, True said.
Light rail service was suspended on the N-Judah line and shuttles were set up to serve inbound and outbound riders until the problem was resolved around 12:20 p.m., True said.
The cause of the derailment is under investigation.
