Three service members who handled a suspicious package that was sent to an Illinois air force base were taken to hospital Wednesday after developing rashes, officials said.
They were all released after a brief medical exam, a spokesman for the Scott Air Force Base said.
"They were just experiencing some skin irritation," Lieutenant Benjamin Garland told AFP.
The military mail center and adjacent buildings were immediately evacuated after the package was discovered around 9:30 am (14:30 GMT)
Some 13 other people who were in the vicinity of the package were also evaluated by medical personnel.
Officials said there is no immediate threat to surrounding communities.
Garland declined to confirm reports that a sulfur-like smell came from the package or comment on what kind of suspicious material the package contained.
"It is currently under investigation," he said.