Eleven people fell ill after a suspicious letter was opened in an administrative building at Joint Base Fort Myer-Henderson Hall in Arlington, Virginia, on Tuesday, according to the Arlington County Fire Department.
Of the 11 individuals who felt ill, three were transported to a local hospital and are in a stable condition, a spokesperson for the department said.
The spokeperson said the incident response is being scaled back, however, the investigation remains ongoing.
A corporal, gunnery sergeant and a colonel all exhibited symptoms of a burning sensation on their hands and face, according to Specialist Nicholas Hodges who spoke to CNN from the base.
One individual had a nose bleed.
It is unclear at this time whether the letter was opened and who exactly handled it.
The incident occurred in the 1 p.m. hour in building 29, known as Henderson Hall, where Marines and civilians work.
A spokesperson for Arlington Fire Department told CNN they are assisting in the matter.
This story is breaking and will be updated.