Authorities are trying to identify a powdery substance mailed to the Christian Broadcasting Network headquarters in Virginia Beach.
CBN spokesman Chris Roslan says four people opened the envelope containing white powder Wednesday morning. Officials don't suspect the powder to be harmful, but turned off the air conditioning and evacuated the building as a precaution.
Virginia Beach fire spokesman Tim Riley says the department's preliminary tests have ruled out several common biohazards, including anthrax, botulism and ricin. The substance was sent to the state laboratory in Richmond for further testing.
Roslan says the two employees who opened the letter, a security guard and a U.S. postal service inspector were placed on precautionary medical watch.