A suspicious package, discovered at about 9:30 CT, at a U.S. Air Force base about in Illinois, 15 miles east of St. Louis, prompted a temporary closure of parts of the facility on Wednesday.
Lieutenant Neil Samson, public information officer at Scott Air Force Base, said the three sickened people were evaluated and released but that another 13 people were still being checked out and decontaminated on site by emergency personnel.
The base immediately sent the three to a nearby hospital as a result of possible chemical exposure.
Chicago Tribune reports that the incident started a little after 9 a.m. in building 1650.
Samson said workers who came in contact with the package inside the base's mail center, had developed rash-like symptoms after handling it, prompting them to call base emergency officials.
Samson said there was no immediate threat to the surrounding community.
Tribune reported that the three mail handlers have been treated and released from the hospital.
AFB officials asked any personnel who visited the Post Office Wednesday and were exhibiting any abnormal symptoms or skin reactions to report to the a hospital clinic or base.
Several buildings immediately adjacent to the mail facility, including the base bowling alley, were also evacuated as a precaution.
The education center, bowling alley, Information Tickets and Tours office and the Airman Family Readiness Center buildings are closed until further notice, base officials said.
The main gate, however, remained open as was most of the base.
Another Scott Air Force Base spokesperson could not say why the base believed the package was suspicious.
The base, located near Belleville, Illinois, houses some 13,000 personnel and is home to U.S. Air Force active, reserve and National Guard air units, officials add.