"The first car kept jumping up and down like it was about to derail," passenger James Rice told ABC7.
That is exactly what happened next. Around 10:30 a.m., a five-car Richmond-bound train was just about to pull into downtown Oakland's 12th Street station when it derailed just 200 feet from the platform.
"What we do know is that the front cab, the front car, three of the four wheels came off the track way," explained BART Chief Spokesman Linton Johnson. "How they came off the track way, we have no idea at this point."
BART workers and Oakland firefighters evacuated 75 passengers from the underground tunnel.
"The lights went out. The power wouldn't come back on and we was all wondering what was going on," Rice recalled. "We figured it would start back up but it didn't, so we was all stuck on the train. We were down there for about 30 minutes."
BART says the train was traveling at low speed, less than 30 mph, and running on automatic pilot. Just two passengers suffered minor injuries including a man who had a seizure.
Derailments do not happen on the BART system very often, but this was the second time that a train has derailed at the 12th Street station in the last 10 months. February's crash was a result of two trains colliding. No one was injured in that incident and BART says driver error was the cause.
About four hours after Wednesday morning's crash, the train was put back on the tracks and sent to the repair yard, empty. The 12th Street station only closed for about 30 minutes as investigators looked for a cause of the derailment.
Officials say everything is a possibility right now including the day's frigid weather which can cause the tracks to shrink.
"We're going to look at everything," Johnson said. "We have no idea what caused this derailment as of this point, but we're bound and determined to get to the bottom of it. That's for sure."
Surprisingly, Wednesday's derailment did not cause any major disruptions for the BART system. Officials say the portion of the track where the train derailed remains closed, but as of Wednesday evening, there is only a two-minute delay for the Fremont-Richmond line.