Authorities are trying to figure out what caused a four-car Chicago Transit Authority train to derail overnight, leaving one person with minor injuries.

Fourteen passengers were aboard the southbound Red Line train when it derailed at around 2 a.m. as it was approaching the 95th Street station.

CTA spokeswoman Sheila Gregory says the passengers were able to walk to the nearby platform.

The derailment occurred while the train was on ground-level tracks and all four cars remained upright.

The accident comes a week after a Green Line train derailed, injuring 14.

Authorities blamed that incident on the train's operator.

Click here for a video report from MyFOXChicago.com.