German emergency services evacuated the visa section of the United States consulate in Berlin on Thursday after an employee fell ill after opening a suspicious envelope that was handed to her by a visitor, a police spokesman said.
Television footage showed investigators in special protection suits at the building and staff waiting outside.
"The lady felt unwell and reported a metallic taste in her mouth," the police spokesman said.
A spokesman for the fire services, who were also at the scene, said three people had reported breathing difficulties.
The U.S. embassy could not immediately be reached for comment.