The Chicago Transit Authority is rerouting Red Line subway trains to elevated tracks because of reports of someone on the tracks.

An “unauthorized person” was spotted at 3:07 p.m. on the Red Line subway tracks between the Grand and Chicago stations, according to CTA spokesman Jon Kaplan. Power to the subway was cut and trains were rerouted as Chicago police responded to search the area.

All service between Fullerton and Cermak/Chinatown temporarily operated along the Loop elevated tracks, making stops at Armitage, Sedgwick, Chicago, Merchandise Mart, Clark/Lake, State/Lake, Washington/Wabash, Adams/Wabash and Roosevelt, according to CTA service alerts.

The tracks were cleared and normal service resumed with residual delays by 3:39 p.m., Kaplan said.