Quarantine lifted after mystery powder sickens 3 in Alameda

Three people were sickened at the Alameda U.S. Customs and Border Protection office when an employee opened an envelope with a powdery substance inside. Three people were sickened at the Alameda U.S. Customs and Border Protection office when an employee opened an envelope with a powdery substance inside. Photo: KTVU Photo: KTVU Image 1 of / 7 Caption Close Quarantine lifted after mystery powder sickens 3 in Alameda 1 / 7 Back to Gallery

Three people said they felt ill and about 20 others were quarantined Wednesday after an employee in a U.S. Customs and Border Protection office in Alameda reported opening an envelope that contained a powdery substance, officials said.

The incident occurred on the 2400 block of Mariner Square Loop about 12:45 p.m., said Juan Medrano, a spokesman for the Alameda Fire Department. Hazardous materials personnel responding to the report, however, said they couldn’t find a substance and lifted the quarantine shortly before 4 p.m.

The envelope, which was addressed to the agency and delivered by a private mail carrier, was taken to a lab for further investigation, officials said. They said two of the three people reporting illness were taken to a hospital as a precautionary measure.

“Once we identify what it is,” Medrano said, “we can figure out how to deal with the substance itself and what levels of decontamination are needed.”

Kimberly Veklerov is a San Francisco Chronicle staff writer. Email: kveklerov@sfchronicle.com Twitter: @kveklerov