Several people were reportedly sickened Friday morning after a package smelling of ammonia was opened inside the IRS building near Union Station.
Kansas City firefighters were called to the building in the 300 block of West Pershing Road about 9:45 a.m. Friday.
Officials said about 10 people were treated for symptoms such as nausea and vomiting.
James Garrett, a spokesman for the Kansas City Fire Department, told The New York Times that employees complained of nausea, diarrhea and vomiting.
Lucy Martinez, a spokeswoman for the federal Department of Homeland Security, said seven people were hospitalized but were later released.
Garrett said the injuries were believed to be “not serious at all.” He said he did not know what was inside the package, and that the package’s contents and the sender’s intent would be the subject of a separate federal investigation.
Attempts by The Star to reach Garrett for comment were unsuccessful.
A local hazardous materials team turned the envelope over to the United States Treasury Inspector General for Tax Administration, which is leading that investigation.
According to The Times, an IRS spokesman said Friday that the agency was still gathering information, and the Kansas City Police Department directed questions to fire officials.
The building was not evacuated as the situation was investigated, officials said.