Three people were hospitalized in stable condition, according to the Arlington Fire Department, which assisted in the investigation. They've since been released.

WASHINGTON — The Naval Criminal Investigative Service and the FBI are investigating a suspicious letter received at Joint Base Myer–Henderson Hall in Arlington, Virginia on Tuesday.

A hazardous materials team was dispatched after the letter containing an unknown substance sickened 11 and sent three to the hospital. The three have since been released from the hospital.

The letter was received at around 3:30 p.m. on the Marine Corps side of the base, according to a news release from Joint Base Myer-Henderson Hall.

“Several Marines are receiving medical care as a result of this incident,” said a Pentagon statement Tuesday evening, before their release.

Symptoms among those affected included nosebleeds and burning hands, according to sources familiar with the situation.

“Personnel in the affected building took immediate preventative measures by evacuating the building,” the Pentagon said. “Base officials … are coordinating with local hazmat teams and FBI.”

The Arlington facility is headquarters to service personnel working throughout the D.C. region.