A glitch in operation of a network router in a data center that supports Bay Area Rapid Transit – a heavy-rail public transportation system that services the San Francisco Bay Area, including parts of the Silicon Valley – brought the entire system to a halt Monday evening, causing all of its 28 trains to unload their passengers at nearest stations.

BART spokesman Linton Johnson said the router was located in a data center that is owned and operated by the transit agency, but declined to say where in the region the “fairly sizable” IT room was located.

The data center is part of the agency's Operations Control Center, which controls train operations, electrification, ventilation and emergency response systems.

The issue was caused by two redundant routers, according to the San Francisco Chronicle. Even though the two routers were meant to back each other up, when one of them failed on Monday, the other did not transmit data as planned.

The issue prevented managers from viewing train movement through a monitoring system they use. BART said the outage did not create a safety hazard, as the router issue did not affect computers that control train movement.

BART service was halted around 7:35 p.m. and resumed around 9:50 p.m.