Two workers at a post office distribution center were sent to an area hospital Thursday night after they encountered a leaking package while sorting mail.

According to the Kent Fire Department, both workers complained of respiratory distress and coughing after finding a package that appeared to be leaking some sort of fluid. The box was placed on the loading dock and members of the Kent Fire Department RFA responded to the call and treated the two workers. As a precaution, the fire department’s Hazardous Materials Response Team was called in to analyze and identify the liquid.

Fire officials discovered that the contaminated box encountered by the workers was not the source of the leak, but that it came from a different package, which was located and analyzed by the hazardous materials team.

“As is common in situations such as this, without more information about the material it is almost impossible to determine exactly what the material was given that there are tens of thousands of different chemicals and compounds,” the Kent Fire Department said in a press release. “The HMRT was able to determine that the material was a respiratory irritant but that it was not explosive, radioactive, or immediately dangerous to life, and that it was stable.”

The leaking and contaminated packages were sealed and turned over to postal officials for further investigation.