The Die Hard star has since issued an apology after having been photographed entering and leaving a California pharmacy without a face mask on Sunday.
In an exclusive statement to PEOPLE he said ”It was an error in judgment" and advised everyone to "Be safe out there everyone and let's continue to mask up."
The 65-year-old star was seen on Twitter leaving a Rite Aid pharmacy in Los Angeles, casually dressed, wearing a baseball cap and a scarf around his neck - which he could have used as a mask.
The A-List actor was asked to leave the store by an employee, according to Page Six.
Once posted online, the photo continued to be shared on social media, with criticism for the star growing with each retweet - by Tuesday Willis was trending on Twitter.
California is currently in the grip of a rapidly spreading second wave of the virus with the NYTimes reporting that there were at 724 new coronavirus deaths and 45,868 new cases reported in California on Jan. 12.
