Four California police stations receive white powder envelopes

Four police departments in Alameda County, California, were recently sent envelopes containing white powder, prompting the U.S. Federal Bureau of Investigation to begin an investigation.

Police departments in Berkeley, San Leandro, Hayward and Union City each received a white powder-filled envelope on the same day as part of their ordinary mail delivery. In each of the cases, the powder was deemed harmless, according to

Aisha Knowles, a spokeswoman for the Alameda County Fire Department, said it was still unclear as to whether the incidents are connected. Berkeley police said they were in contact with the police departments in Hayward and San Leandro to determine if there is a link, according to

The Berkeley Police Department has launched a criminal investigation into the matter and has notified the FBI, who intended to take an active role. United States postal inspectors are currently trying to track down who sent the envelopes.

"There's state statutes that have been violated and federal statutes, so it is very, very serious," Jeff Fitch, a United States postal inspector, said, reports.

Investigators would say little about the envelopes except that each contained a note, none had a return address and all were postmarked at the Oakland Main Post Office. They said that more police departments could receive similar envelopes in the coming days.