Overhead Muni wires on Fillmore Street were damaged Wednesday afternoon after being contacted by the parallel bars that connect it to a bus.
The exact cause of what went wrong is unknown, but the bars that attach a trolley coach to the wires made contact with them around 4:26 p.m. at the intersection of Fillmore and Sacramento streets causing the lines to lose power.
The 41-Union and the 22-Fillmore were affected, according to San Francisco Municipal Transit Agency spokesman Paul Rose.
Power to the lines has since been restored and the 41 line is up and running its normal route, but the 22 line remains affected. Rose said shuttles are in place beginning at McAllister.
Service was restored to the 22-Fillmore line later in the evening.