Blue Line trains were running with delays after service was suspended Wednesday between UIC-Halsted and Cicero stations due to an unauthorized person on the tracks.
Trains were standing at 3:45 p.m. near Kedzie-Homan on the West Side, the Chicago Transit Authority said in a statement. Service resumed by 4:30 p.m., the CTA said.
The transit agency said it was alerted for an unauthorized person on the tracks, but authorities could not locate anyone.
Some trains may be running express to close up gaps in service, the CTA said.