SEATTLE — Seattle’s new light rail service through the downtown transit tunnel was disrupted for hours today when an electrical problem knocked out signals that keep trains and transit buses separated.

Bus service through the 1.3-mile tunnel remained normal and trains continued to operate as scheduled between the Stadium Station near Qwest and Safeco fields, south of the tunnel entrance, and the southern end of the line near Seattle-Tacoma International Airport, Sound Transit spokesman Geoff Patrick said.

Sound Transit opened the 13.9-mile light rail line between downtown and the airport Saturday. A 1.7-mile extension to the airport is scheduled to open by the end of the year, and a suburban expansion north, south and east of the city is planned that would take the system to 55 miles by 2023.

No one was injured in the disruption, which began shortly before 9:30 a.m. with “some type of power anomaly that’s not been identified” in the Pioneer Square Station near the southern end of the tunnel, Patrick said.

The problem triggered a shutdown of the signal system, which includes monitors that provide the location of each bus and train moving through the tunnel, he said.

Buses have room to maneuver around trains at each station but not within the narrower passages between stations.

Patrick said electricity within the tunnel never was out. Two trains moving through it when the signal system went down were guided into stations manually by transit workers, passengers disembarked and the trains were driven out of the tunnel, he said.

“Well, it kind of spoiled my day,” commuter Jehron Thogersen told KING-5 TV. “I realize they have some wrinkles to iron out.”