GO trains on the Lakeshore East line are running at reduced speeds due to a "major signal problem" near the Whitby station, Metrolinx said Tuesday. 

Service between Oshawa and Ajax had completely ceased for several hours earlier due to the signal issue. The problem has not been resolved, Metrolinx said, but trains are running, though more slowly than usual. 

Trains were already running behind schedule due to an earlier police investigation nearby Scarborough GO station. Police received a report about a woman apparently near the tracks but nothing came of their efforts to locate her. 

 Metrolinx spokesperson Anne Marie Aikins said passengers should check online for updates to schedules.