Marines fall sick after opening envelope in US military base

An envelope containing an unknown substance was opened at a US military base near Washington, leaving 11 Marines sick and prompting the FBI to launch an investigation.

A gunnery sergeant opened the envelope received on Tuesday at Joint Base Fort Myer-Henderson Hall in Arlington, Virginia. People who were exposed reported symptoms, including itchy hands and faces and bloody noses, a Marine official told NBC News. The building was evacuated immediately.

A law enforcement official said field tests for the letter all came back negative for any harmful substance, but the FBI is transporting it tonight to its lab in Quantico for further analysis, CNN reported. The official said the envelope was addressed to the Marines' headquarters battalion on the base, not to an individual, reports PTI.

"Shortly after receiving the letter, 11 people started to feel ill and caused the evacuation of the building," Major Brian Block, a Marine spokesman said. After the evaluation of 11 people, three personnel were transported in stable condition for further medical evaluations. The building was screened and cleared. "The letter was removed, and NCIS (Naval Criminal Investigative Service) and FBI are conducting a joint investigation," he said. The law enforcement official said the text of the letter contained derogatory, at time unintelligible and ranting language, CNN reported.