A “suspicious package” containing an unknown white powder and political materials has caused several individuals to fall ill at a U.S. military base in Maryland, as reported by various sources.

In response to the threat, Joint Base Andrews, located near Washington, D.C., issued a statement highlighting precautionary measures. “The building and adjacent facilities were evacuated, and a security perimeter was established in the area,” according to CNN, citing the base’s official communication.

Emergency responders at Joint Base Andrews quickly assessed the situation, determining there were no immediate dangers. The investigation has now been handed over to the Office of Special Investigations.

The package was received and opened on Thursday within a building that accommodates the Air National Guard Readiness Center. Sources involved in the investigation revealed that the package contained a white powder, though its exact composition remains unknown.

Initial tests conducted by a HAZMAT team did not identify any hazardous substances. However, following the package’s arrival, several individuals were taken to the Malcolm Grow Medical Center located on the base. The current conditions of those exposed have not been disclosed.

Authorities are also examining the political materials included in the package, although further details on this aspect have not been provided.

Senior political figures — including President Donald Trump, who was most recently there on Wednesday — frequently pass through Joint Base Andrews base when traveling. It is also home to some 60,000 Airmen and their families,

An investigation into the matter is ongoing.