SAN FRANCISCO (CBS SF) — Drivers on the Bay Bridge were confused as they were greeted by disco-like flashing lights on Wednesday evening. They weren’t alone; Caltrans didn’t know why the lights were flashing, either.

The vertical lights around the tower of the Eastern portion of the span (Oakland side) were cycling on and off, as were the lights inside the tunnel.

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KPIX 5 reporter Wilson Walker took video of the phenomenon as he crossed the bridge after 6:30 p.m. Caltrans said the lights began blinking at about 5:58 p.m.

Caltrans sent electricians to the bridge to see if they could determine what the issue is and they turned the blinking overhead cable lights off at 7:47 p.m.

They believe there may have been a possible shortage at a substation, but they said they won’t be able to confirm this until Thursday. The electricians left the bridge before 10 p.m. Wednesday evening.

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Caltrans has not ruled out the brutal weather as playing a factor in the potential shortage. All essential lights for the bridge are still on and the incident did not appear to affect traffic at all.