An Amazon warehouse visited this week by chief executive Jeff Bezos confirmed its first employee coronavirus case, according to a message sent to workers on Thursday.

The employee who tested positive for Covid-19 was last at the site on Monday, according to the update Amazon sent. “Consistent with our daily processes, the site has undergone enhanced cleanings since the associate’s last day,” said the message. Amazon declined to comment.

Bezos made a surprise visit Wednesday to the warehouse, called FTW6, which is just north of Dallas Fort Worth International Airport. It’s among more than 100 similar sites around the US where employees are busy trying to meet a surge in online orders from customers sheltering at home.

Bezos walked through the facility wearing a face mask, waving to workers and flashing thumbs up. He also visited a Whole Foods location, and Amazon posted video of his tours on Twitter.

The FTW6 warehouse has been cleaned multiple times since the infected worker was last in the facility, according to someone at the company who did not wish to be named. – Bloomberg