New York City police evacuated the newsroom and executive offices of the Wall Street Journal at the Dow Jones building on Wednesday after the mailroom received several envelopes containing a white powder. At least four of the envelopes were opened. Others were left unopened in the mailroom, police said. Five workers were being decontaminated as a precaution, a Federal Bureau of Investigation (FBI) spokesman said. A newspaper spokesman said the letters—sent from Knoxville, Tennessee—were addressed to several executives. Law-enforcement authorities said they are trying to determine the nature of the powder.