UPDATE 8.15am: Perth Underground and Esplanade train stations were evacuated this morning as authorities tried to determine the source of an alarm.
Public Transport Authority spokesman David Hynes confirmed Underground was evacuated about 7.50am. Commuters at Esplanade Station were evacuated a short time later.
Both stations were reopened about 8.15am.
Trains were stopped in and out of the station for more than half an hour.
Transperth said the issue caused delays to services on Joondalup and Mandurah lines.
A Department of Fire and Emergency Services spokeswoman said initial information suggested it was a “fault alarm” and not a fire.Train services have resumed but Transperth warned commuters to expect 25 minute delays while the backlog was cleared.