Several people were hospitalized from Joint Base Andrews near Washington after receiving a suspicious package containing white powder, sources said Thursday, CNN reports.

As a precaution, the people in the building to which the package was delivered, as well as in an adjacent facility, were evacuated.

Emergency services are working at the scene and have determined that there is no immediate threat to people’s lives.

The composition of this substance has not yet been determined, but hazardous materials specialists have made a preliminary assessment that it does not pose a risk.

The package also contained materials with political propaganda.

Joint Base Andrews is the military base through which American VIPs such as the president, vice president, and cabinet secretaries regularly travel on official business.