The transit agency first said this was due to a blown insulator but now say that the delays were caused by a debris fire on the tracks.
BART says crews have extinguished the smoldering debris and service is returning to normal.
They say to expect residual delays.
Stay with ABC7 News for details on this developing story.
We are single tracking through the Transbay Tube due to an equipment problem on the tracks. Currently experiencing major delays.— SFBART (@SFBART) June 24, 2017