The failure of air compressors in two consecutive new train cars left a BART train inoperable on Monday, leading to the evacuation of 421 passengers from the middle of train tunnel in Oakland.

BART says it is still investigating, but spokesperson Alicia Trost says in a statement, "Our preliminary finding is that we had two adjacent cars on the train that had their air compressors malfunction causing a failure of train line communication between the cars. This resulted in the train failing in a safe mode and being rendered unable to move."

The incident happened on Monday morning around 10 a.m., and the train was stopped between Lake Merritt and 12th Street stations, as ABC 7 reported Monday. Passenger Jeff Estrellanes told the station, "It felt almost like someone just pulled the plug out from the train and everyone just got thrown back. I actually got thrown back and fell back into my chair."

Riders were stuck in the disabled train for an hour before BART decided to conduct the evacuation, as KPIX reports. It was decided that passengers would walk along the evacuation path a few hundred feet to 12th Street Station — and the entire ordeal caused systemwide delays.

"This is the first time we have had a failure of this nature on the new cars,” Trost says. “We are analyzing the failure and determining if any modifications are needed to the cars."