New York Mayor Michael Bloomberg received a threatening letter containing a substance that tested positive for the poison ricin, the NYPD said Wednesday.
The anonymous letter to Bloomberg was opened Friday in the city's mail facility, and the next day, three emergency service officers, who had seized the letter, developed diarrhea and other "minor" symptoms for ricin exposure, NYPD spokesman Paul Browne said.
An identical letter to the director of Mayors Against Illegal Guns, co-founded by Bloomberg, was opened Sunday by a worker in the group's Washington office, authorities said. That worker did not develop symptoms, Browne said.
Browne declined to give details of the letter, but a federal law enforcement source said the threats were "along the lines of 'This is what's going to happen to you if you come for my guns.' " The source said it is believed that both letters were sent by the same person.
Bloomberg Wednesday said he wasn't scared off.
"The letter obviously referred to our anti-gun efforts, but there's 12,000 people who are going to get killed this year with guns and 19,000 who are going to commit suicide with guns," he said during an official stop at a Manhattan synagogue. "We're not going to walk away from those efforts."
The letters were postmarked May 20 in Shreveport, La., the American Postal Workers Union said, citing a safety bulletin to workers from the U.S. Postal Service.
"The substance involved was not in a form that could be inhaled or otherwise readily ingested," the federal agency said in the Tuesday alert.
Additional tests of the substance are under way in specially equipped labs, the alert said, and law enforcement officials have been searching the mail stream for any additional letters.
They were also trying to determine whether the letters are linked to other recent ricin cases, including that of a Mississippi man charged with sending ricin letters last month to President Barack Obama, a Mississippi senator and a local judge.
The address in the letter to Bloomberg had looked suspicious Friday to a civilian worker at the city's mail facility on Gold Street in Manhattan, Browne said.
"This letter raised suspicions before it was opened, so it was opened in a protective manner," he said.
In such cases, the mail is put in a sealed containment box with access via gloves, allowing the mail worker to open an envelope without touching it or being exposed to it, Browne said.
Inside was a pink-orange, oily substance, the same sort of substance in the Washington envelope, Browne said.
Emergency service officers then took the letter, he said.
The substance in the New York letter was tested locally and also Wednesday at the National Bioforensic Analysis Center in Maryland, Browne said. Both tests showed positive results for ricin, he said.
The Washington letter also was sent to the Maryland lab, Browne said. He said he does not know whether that letter tested positive for ricin.
Civilian personnel in New York and Washington who came in contact with the opened letters have not developed symptoms associated with ricin exposure, Browne said.
Noting that ricin can be deadly, Browne said the officers who were exposed were being monitored at hospitals and that their symptoms had abated.
Mark Glaze, director of Mayors Against Illegal Guns, could not be reached Wednesday.
Bloomberg, who co-founded the group in 2006 with Boston Mayor Thomas Menino, has been increasingly out front and visible in lobbying for tougher gun laws. He's gone to Capitol Hill, spearheaded commercials on the topic and funded the group with millions of dollars of his own money.
When asked, Bloomberg said Wednesday he was not angry. "There are people who I would argue do things that may be irrational, do things that are wrong. But it's a very complex world out there. And we just have to deal with that."