Envelopes containing non-toxic powder were sent to JPMorgan Chase & Co. (JPM), Citigroup Inc. (C) and The Wall Street Journal on Tuesday, Reuters reported, citing New York Police Department spokesman Paul Browne.

A total of 10 envelopes with white powder have been sent over the last two days, according to the Reuters report, including envelopes sent to several Wells Fargo & Co. (WFC) branches on Monday. In several of the cases the material was identified as corn starch, Browne told Reuters.

At least some of the envelopes included notes saying "Happy May Day," Reuters reported.

A spokeswoman for Dow Jones & Co., owner of the Wall Street Journal and this newswire, said "we're investigating a letter received in our mailroom."

A Citigroup spokeswoman declined to comment. A JPMorgan representative wasn't immediately available for comment.

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