Several Marines are receiving treatment after being affected by an unknown substance found in an envelope.
The envelope was received at Joint Base Myer-Henderson Hall, next to Arlington National Cemetery in Arlington, Va. The building where the envelope was opened was evacuated immediately.
The Marines later tweeted that “several Marines” were receiving medical care.
A spokesperson for the Metropolitan Washington Airports Authority Fire Department said 3 people are being treated, according to ABC News. {mosads}
The Arlington, Va., fire department tweeted that 11 people began feeling sick after the letter was opened.
Three of the patients the fire department transported are in stable condition, but an investigation is ongoing.