Hey, remember how a portion of the Bay Bridge burst into flames on Monday night? It happened again yesterday afternoon at exactly the same spot, and officials can still only speculate on the cause of the conflagrations.

It was noon Wednesday when flames arose yet again, from exactly the same spot on an expansion joint between the Yerba Buena tunnel and the new suspension span on the eastbound side of traffic.

According to Caltrans spokesperson Leah Robinson-Leach, the fire was extinguished by 12:14, but lanes #1 and #2 on the bridge had to be closed for an investigation into the blaze, snarling traffic until 1:50 p.m.

Robinson-Leach told ABC7 that both "fires damaged the rubber seal on the joint, which protects it from debris and saltwater, and repairs will be needed." According to the Chron, crews have already repaired the area once, following Monday's fire.

But why did the twin fires happen in the first place?

“The investigation is ongoing,” Robinson-Leach said to the Chron, “but it is believed that the cause was flares left by work crews for maintenance operations.”

Assistant San Francisco Fire Chief Tom Siragusa isn't so sure, saying that "there was nothing at the scene to indicate what may have started the fires."

However, "a source familiar with the investigation" tells the Chron that on Monday a road flare "got caught in the rubbery material that covers the expansion joint" and ignited. Then Wednesday, "a second flare appears to have ignited the rubbery material once again after it was hit by traffic and rolled about 200 feet to the same spot."

If there's a third fire, perhaps that one will be the investigative charm. For, as the Chron reports, that's when SFFD "will work with the California Highway Patrol and Caltrans to figure out the cause."

Previously: Bay Bridge Catches Fire, Expansion Joint Junk Might Be To Blame