TORONTO, Ont. – Subway service on all lines were on hold in all directions for about 40-minutes due to signal problems, Friday.

TTC spokesperson Jessica Martin told 680News there was a communication issue between the traffic control centre and the signal system.

Supervisors were called in to assist.

“We have supervisors en route to main towers where they can manually control the signals. Subway service should resume at that time,” she said.

Jessica said that with the assistance of the supervisors and technicians in the traffic control centre, they were able to resume full service around 9:15 p.m.

On Twitter, TTC spokesman Brad Ross apologized for the disruption and stated that “At no time was safety ever compromised, which is why TTC institutes a stop and stay.”

Ross said the system that controls signals and allows transit officials to see trains on all lines failed. He said this kind of occurrence is very rare and that transit officials are investigating to determine the cause.