NEW YORK (CBSNewYork) -- The federal courthouse in Brooklyn was locked down Tuesday afternoon, after suspicious white powder was discovered.
The Eastern District of New York federal courthouse at 225 Cadman Plaza East in Brooklyn was locked down as of 4:45 p.m. and no one was leaving, officials told CBS 2.
Someone at the courthouse received a letter containing white powder, police confirmed. It was not clear to whom it was addressed or who opened it, but first responders did find it to contain a "suspicious" white powder, officials said.
A note inside the letter said the substance was anthrax, law enforcement sources told 1010 WINS. It was not known Tuesday night whether the letter really did contain anthrax or anything else suspicious.
Twenty people were exposed to the powder, and one of them had direct contact with it, according to the FDNY.
Three people had to be decontaminated, while the rest were treated for exposure.
An investigation into the incident continued Tuesday night.
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