PHILADELPHIA (CBS) — An El train partially derailed Saturday along SEPTA’s Market-Frankford Line.

It happened around 11 a.m. at SEPTA’s Spring Garden stop at Spring Garden and Front Streets.

SEPTA said the train was travelling eastbound from Center City to Frankford Transportation Center and was slowly crossing over from the eastbound to westbound sides because of maintenance work when the lead car jumped the tracks.

(credit: @ilovemesomegoat)

SEPTA said approximately 30 people were aboard the train, and all were safely evacuated.

One person was treated at the scene for heat exhaustion and released. No other injuries were reported.

SEPTA said crews were working on the tracks at Spring Garden at the time of the accident.

Officials are investigating the cause of the derailment.

SEPTA was running shuttle buses between 8th Street and Berks.