An envelope filled with an unknown substance caused a scare Wednesday at the Bronx Family Courthouse.

Officials say one floor of the building on 161st Street and Sheridan Avenue was evacuated after the envelope was opened by a clerk. Hazmat crews were called to the scene and the courthouse was soon sealed off.

The envelope, filled with an unknown white powder, was addressed to a courthouse judge. "Nobody knew what was the problem," says Jeff Gonzalez, who works in the courthouse. "The correction officer just said to leave."

Officials say seven people were exposed to the substance, one of who was taken to the hospital. None showed symptoms of being seriously ill. The substance has not yet been identified.