At least 20 people have been quarantined after an employee opened envelope with a suspicious powdery substance at the Customs and Border Protection office in Alameda, California. An employee reported feeling ill immediately after opening the envelope on Wednesday afternoon. Two others also had a bad reaction, and were treated at the scene. One person was reportedly taken to the hospital. According to KTVU : Emergency crews quarantined approximately 20 employees who were in the vicinity when the envelope was opened. That quarantine was lifted around 3:30 pm. In a statement released by the U.S. Customs and Border Protection agency, officials said it was unknown if the employee’s illness was a result of opening the envelope. Chopper video from KTVU showed hazmat teams, as well as firefighters and ambulances on scene. Dozens of other people were seen standing outside the building inside an area roped off with police tape. A portion of Mariner Square Parkway was closed as officials investigated. BREAKING: Federal building in Alameda evacuated after employee opens package, falls ill https://t.co/aikp1ylW51 pic.twitter.com/YPGKGYMmPR — KTVU (@KTVU) February 24, 2016