My first thought, they’re all huddled in the back room while the safe is being cracked open by robbers.
Or out back of the restaurant smoking some dope.
My first thought was the cook and the waitresses got into an argument and they all walked off the job...
Yours is more likely - in which case this man should have called the police. And if I’m right - he should have called the police too. Not everyone who walks into an empty business is an innocent.