Police say white powder sent to Wall Street Journal building in New York City was harmless, likely flour, the AP reported.
Employees at News Corp's Dow Jones headquarters were evacated after three executives received envelopes containing the powder and another 10 were discovered in the mail, a company spokesman said.
The building contains Dow Jones as well as its Wall Street Journal daily business newspaper. The New York Police Department and New York Fire Department's Hazmat teams are investigating.
The letters were sent to Wall Street Journal Managing Editor Robert Thomson, Dow Jones Chief Executive Les Hinton and Journal Editorial Page Editor Paul Gigot, according to a source familiar with the matter.
U.S. authorities have been on alert for mail with white powder in it since 2001 when envelopes laced with anthrax were sent to media outlets and U.S. lawmakers, killing five people.
The envelopes were found on the 11th floor, where News Corp Chief Executive Rupert Murdoch and Thomson have offices, Wall Street Journal spokesman Robert Christie said.
Thomson was not in the building at the time. Murdoch's whereabouts are unknown. The 11th floor was evacuated, as was the ninth floor where the mailroom is located.
The building is on Liberty Street in lower Manhattan, close to the Ground Zero site where the World Trade Center stood before it was attacked and destroyed on Sept. 11, 2001.
A News Corp spokeswoman was not immediately available for comment. News Corp's headquarters is in Midtown Manhattan.
The envelopes bore a Knoxville, Tennessee, return address, Brown said. It is unknown what the postmark says on the envelopes or whether they contained notes.
The incident follows others late last year in which powder was sent to media outlets and financial institutions.
In October, letters, many containing white powder, were sent to Chase bank offices and two other financial institutions in several states. They also were sent to The New York Times headquarters in New York and to Thomson Reuters Corp's Reuters newsroom in New York.
The letters sent to the financial institutions warned "it's payback time," according to a text released by the FBI in October.
- AP and Reuters contributed to this report.