OAKLAND, Calif. — The commuter train that struck and killed two San Francisco Bay Area transit workers didn’t have a front-facing video recorder, but interviews, inspections, audio recordings and camera footage from the train’s cab should provide enough evidence to determine a cause, a federal investigator said Sunday.

Jim Southworth, the National Transportation Safety Board’s railroad accident investigator-in-charge, confirmed that Saturday’s accident involved a Bay Area Rapid Transit train that wasn’t carrying passengers because of the strike that has shut down the system since Friday.

But whether the work stoppage by members of the system’s two largest unions or the way BART management deployed non-striking workers played a role in the fatalities will not be known for weeks or months, Southworth said.

With no indication that the striking BART workers would be back on the job Monday, the region was preparing for a day of gridlock on freeways and bridges clogged with commuters who would usually travel by train.