Suspicious unclaimed objects and persons

This was a sign I saw on a train I took today. I read it over and over.

Which adjectives are describing the word "persons"?

<Possibilities and the outcome>

"Please inform the station staff or train crew immediately..."

nil (0) : if you notice any (0) persons in the station or on the train.

  → So practically, no one can be at in the station or ride the train

suspicious : if you notice any suspicious persons in the station or on the train.

 → The most plausible and reasonable choice.

suspicious unclaimed : if you notice any suspicious unclaimed persons in the station or on the train.

 → ... my imagination goes wild...

It really does look suspicious.