11 sickened after letter with unknown substance opened at Joint Base Myer-Henderson Hall

ARLINGTON, Va. - Three people were taken to the hospital after a letter was opened inside a building at Joint Base Myer-Henderson Hall in Virginia.

Arlington fire officials say 11 people began to fall ill after the envelope containing an unknown substance was opened in a consolidated administration building at around 3:30 p.m. Tuesday.

A spokeswoman for Joint Base Myer-Henderson Hall says people in the office on the Marine Corps side of the base said that as soon as the mail was opened, they began feeling poorly and complaining of sore throats.

Personnel were evacuated from the building as a preventative measure, according to the U.S. Marines. Several Marines were among the people treated.

After the evaluation of the 11 sickened victims, three of them were taken to the hospital in stable condition, officials say.

Hazmat teams responded to the scene following the incident. The letter was removed and the building was screened and cleared, according to a base spokesperson.

The FBI and NCIS are conducting a joint investigation on the incident.

Information from the Associated Press used in this report.