Just had to evacuate Civic Center Bart. I think it's a fire? pic.twitter.com/C74GT8v64t— Matt Kim (@LawofTD) September 23, 2018
Scanner recordings also captured the scene: "There's a lot of smoke in this 8-9 car Mark, I'm trying to make sure everybody is off the tracks."
The San Francisco Fire Department responded shortly after 5 p.m. Saturday evening to find people scurrying up the stairs to Market Street.
"They left strollers, they left bicycles, personal property. We found a teddy bear down there. BART Police are trying to get it back to its owner," said SFFD Battalion Chief Bryan Rubenstein.
Once the smoke cleared an entire section of Civic Center station was charred with black smoke. Passengers found the scene unsettling.
Wait for the reveal...— Katie Utehs (@KatieUtehs) September 23, 2018
Insulator that holds the electrified third @SFBART rail blew making a loud pop and filling the station w/ smoke. 10 car train 🚊 evacuated. No injuries. #abc7now pic.twitter.com/0FM1kEv30g
"I think it could have been anything. I think it could have been fire. I see some writing on there, so it could be something graffiti related. Mostly the charring on the wall looks like fire," San Francisco resident Rob Behnke speculated.
The culprit was actually one of the ceramic insulators that support the electrified third rail.
"It was more of a flash. The insulator failed. It makes a lot of noise and a lot of light and smoke, but it's brief and nothing was actually burning," Rubenstein said.
BART engineers are working to replace the insulator. After the smoke cleared and the track was checked, service resumed. No one was injured.