SALINA (AP) — A Kansas post office temporarily shut down Tuesday after receiving a suspicious envelope that authorities later deemed a hoax.

The Salina Journal reports that streets near the Salina Post Office were blocked off most of the day before the Riley County bomb disposal squad determined the envelope didn’t contain an explosive. An investigation is ongoing into who left the envelope, which contained some wires and was addressed to the police department. The police department announced on its Facebook page that investigators have identified a person of interest and are working toward formal charges. Delivery Supervisor Corey Pierce says mail carriers were out on their routes before a customer discovered the envelope.

The incident comes after of a series bombs hidden in packages killed two people and injured four others this month in Austin, Texas, as well as a bomb threat was made at the Pfizer plant in McPherson this week.