SAN DIEGO — The winter storm bringing thunder and lightning to San Diego derailed the Petco Park vaccine super station Wednesday, starting mere hours after staff and volunteers returned from a four-day hiatus.

UC San Diego Health, which administers shots at the site, announced they were pausing operations during the deluge around 12:15 p.m. In a tweet, officials cited “safety concerns related to nearby lightning.”

“The site will reopen as soon as authorities determine it is safe to do so,” the message continued.

Vaccinations got back underway within about an hour, but the damage was done for those hoping for a speedy experience: A snarl of cars waiting for postponed drive-up appointments stretched through downtown and only grew as the day went on, with some residents telling FOX 5 they waited as many as three to five hours to get their shot. The line still stretched about half a mile as of 6 p.m.

It wasn’t immediately clear if anyone’s appointment was officially rescheduled due to the delay, or how many people may have given up during the long wait. UCSD Health typically communicates directly with residents through email and their MyChart app when an appointment does need to be moved.

The downtown super site has dealt with repeated closures, due to local weather, vaccine shortages and kinks in the vaccine supply chain caused by the recent severe winter storm in Texas and other large portions of the country.

Wednesday’s closure came just hours after the site reopened following a four-day pause prompted by short supply. Only limited operations were underway at the site, with appointments focused on getting people their second Moderna shot before the recommended 42-day window between doses closes.

There was some good news for hopes that there wouldn’t be further disruption at the site this week: While some rain showers lingered Wednesday night, clear skies and warmer conditions are expected on Thursday, forecasters said.