The train derailed while approaching the Howard station at about 2:10 p.m., according to CTA spokesperson Catherine Hosinki.
Passengers were assisted off the train and no injuries had been reported as of 2:20 p.m., Hosinki said.
Service was suspended on the Yellow Line after the incident. Red and Purple Line trains were also experiencing "significant" delays after the derailment, according to the CTA.
Bus shuttles are running to accommodate Yellow Line customers, Hosinki said. Customers can also take the No. 97 Skokie bus.