Can't reach my Section 8 tenants

[Christian Nachtrieb]

I might be jumping to conclusions or overreacting, but I'm having an impossible time reaching my tenants. They are Section 8, and 100% of their rent is subsidized by the city so I'm at least getting paid, however both the husband and wife have had their cell phones disconnected and are not responding to messages. I went down yesterday to ring their bell (it's second floor of a multi-family) and no answer.

Should I be concerned? At what point do I call the police if there's a legitimate worry regarding their safety or the safety of their two kids?