Amid routine testing on an unnamed production from Will Smith and Jada Pinkett Smith’s Westbrook, 10 people in Los Angeles tested positive for COVID-19 last week. But after just a few days of quarantine and another battery of tests, all 10 then tested negative, Variety has learned exclusively, underscoring the challenges that production companies and studios face in returning to active television and film shoots amid the ongoing pandemic.

“We have been following the CDC, California State and Los Angeles County guidelines for all of our productions and photo shoots including routine testing,” a Westbrook spokesperson said. “We received 10 positive tests and the crew members quarantined and remain in quarantine. All 10 people were retested and have received negative results. We will continue to follow all official guidelines and safety protocols.”

Variety’s understanding is that those who tested positive were members of the crew and not talent. They will remain in quarantine for a total of 14 days, according to a source familiar with the situation. Those employed on Westbrook sets are tested routinely by the same laboratory.

The only ongoing series currently in production at Westbrook Studios is Red Table Talks, hosted by Jada Pinkett Smith, while Westbrook Media has a number of media shoots in production. The company does not currently have any films in production. Both Westbrook Studios and Westbrook Media are subsidiaries of Westbrook, which was founded in 2019 and also houses a digital content studio, social media management and creative brand incubator, among other businesses.

The 10 confirmed cases at the Calabasas, Calif.-based entertainment company are a matter of public record, published by the County of Los Angeles’ Department of Public Health. Those cases are still on the record despite the recent negative test results.

As Hollywood collectively looks to return to work, Westbrook’s curious case of positive, then negative, coronavirus test results is a possible peek into the difficulties that even conscientious productions with routine testing will have to take into account going forward.