Update: Track obstruction triggers major BART delays in San Francisco

SAN FRANCISCO -- An obstruction caused by an abandoned wheelchair on the tracks at BART's Civic Center station in San Francisco has triggered delays on trains traveling to and through the city, officials said.

In addition to the obstruction, transit officials said BART was also dealing with a trackside equipment problem between Embarcadero and Montgomery stations that was impacting travel.

As for the obstruction, BART spokesman Jim Allison said: "It was not heat-related. It was an unoccupied wheelchair that somehow ended up on the tracks."

The obstruction was serious enough to force the single tracking of trains between the  Montgomery and 16th St Mission stations.

Other trains were being diverted and not going to SF to avoid the growing bottleneck.

MUNI was providing mutual aid buses and honoring BART fares between Embarcadero and Daly City station.    

There was not estimate as to when trains would return to normal service.

Developing story, will be updated.