USA: Hazardous chemical scare at Border Control office, California

Workers at a US Customs and Border Protection office in Alameda County, California were briefly quarantined on Wednesday afternoon after some workers fell ill when an official working at the branch opened an envelope.
The worker who opened the letter, along with two others, began to feel unwell. As a precaution, almost two dozen officials were quarantined.
However, nothing suspicious was found, and the precautionary quarantine measure was lifted after a few hours.