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According to The New York Times, two letters testing positive for ricin were apparently sent to Mayor Michael Bloomberg and a gun control group he founded late last week. A police officer investigating the letters showed some symptoms of exposure, though that number may have expanded to three.

There aren't yet many details on the letters. One, addressed to Bloomberg, was received at a New York City municipal building at 100 Gold Street. The other was sent to the Washington, D.C., office of Mayors Against Illegal Guns, a group co-founded by Bloomberg which has been central to the recent debate over gun control. Neither address is readily associated with either recipient. The Gold Street building is not where the mayor's office is housed; Mayors Against Illegal Guns doesn't appear to have an easily discoverable address near the capital.

Oren Yavin, a reporter for the New York Daily News, provided updates via the New York Police Department.

Ricin letter to Mayor Bloomberg threatened him and had "references to the debate on gun laws," NYPD says. — Oren Yaniv (@OrenNYDN) May 29, 2013

NYPD personnel who came in contact with letter had "minor symptoms of ricin exposure...which have since abated," police said. — Oren Yaniv (@OrenNYDN) May 29, 2013

Police believe that both letters were sent by the same person.