The letters all had traces of what is believed to be the deadly toxin poison "ricin." ABC News reports the FBI is now questioning a person of interest.
The letters were all intercepted at mail screening facilities, which made us wonder how much of the mail destined for local officials gets screened?
A person could argue that Oakland City Hall is a safe place, one with security by the door just for good measure.
But after Wednesday's poison ricin letters sent to New York City Mayor Michael Bloomberg, mail to public officials has come under renewed scrutiny.
"There are people who I would argue do things that may be irrational and wrong," Mayor Bloomberg said.
Clearly, the safety of incoming mail is a major concern to all three of the Bay Area's major cities. So much so, that San Francisco would not allow us near its mailroom. San Jose admitted it uses scanning machines. And those in Oakland wouldn't talk details on their security plan for mail, but did say they keep their officials as safe as possible.
This was close as we could get to the Oakland sorting process, one room from which separate city departments pick up their mail by hand.
Ultimately, all city governments told us that they consider the United States Post Office as a first, major line of defense. Local officials, however, would not tell us much about what they're looking for and how they look for it.
Nationally, the post office handles 535 million pieces of mail every day; 170 billion a year. And yes, they do have occasional scares like the one on May 9 in San Francisco where dust from a fan belt, noticed as white powder, closed the facility and brought out the hazmat teams.
One mail officials told ABC7 News that responses are made on a regular basis and that 90 percent of the time it's something harmless, like someone mailing recipes or something that leaks out.