There was no BART service across the entire system Friday morning due to a computer system failure that occurred before the trains were set to begin running at 5 am Friday.

BART posted a notice about the "systemwide computer equipment failure" at 5:30 am Friday, and subsequently clarified that this failure occurred "following network upgrade work."

Update: As of 10 am, BART said that limited service had resumed in the East Bay, and as of 11:45 am, all BART stations had reopened for service, including on the San Francisco Peninsula. "Expect delays on all lines," BART says.

ABC 7 was out talking to frustrated commuters who arrived at stations only to find out they couldn't get on a train.

BART spokesperson Alicia Trost was out speaking to reporters, and said, "One of the reasons why we don't have service is cause we were actually upgrading our computer network last night. It's a massive ongoing project. We don't just work on it one night a week. And so that is part of rebuilding BART, which is part of being a 50-plus-year-old system. It's unfortunate — absolutely. We're gonna find out what went wrong."

This computer failure is reminicent of one that occurred on May 9, when the entire BART system was similarly disabled due to a computer meltdown on a Friday morning, and only limited train service returned hours into the morning commute.

Fewer people may be going into the office on Fridays these days, but that doesn't mean there aren't thousands of workers who were likely impacted by this, and San Francisco's SFMTA put out an alert warning that its trains and buses would likely be crowded as a result.

Photo by Kace Rodriguez