BEDFORD, N.Y. — A bomb was found in a mailbox at the suburban New York compound of George Soros, the liberal billionaire philanthropist who has been the target of right-wing conspiracy theorists, authorities said Tuesday.

Federal investigators were reviewing surveillance video to determine whether the package had been sent through the mail or delivered some other way, officials said, adding it was also not clear if the parcel was addressed to Soros.

A security officer at the compound about 50 miles north of Manhattan became suspicious of the package Monday afternoon and placed it in a wooded area before alerting the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives, authorities said. Agents came out and safely detonated the device.

“It was not a hoax device,” said the official, who spoke on condition of anonymity because he was not authorized to discuss the investigation.

Another federal official who also spoke on condition of anonymity said the device resembled a pipe bomb and was inside a package placed in a mailbox outside the gates of the compound. It was opened in a secure location just inside the gates, nowhere near Soros’ quarters, the official said.

The Bedford Police Department said the FBI’s terrorism task force was investigating.

The FBI’s New York field office said on Twitter that there was “no threat to public safety” but did not respond to messages seeking comment.

A foundation backed by Soros slammed the political divide in the country and called for more civility.

“The politics of hate that dominates our discourse today in the U.S. and in so many countries around the world breed extremism and violence,” the Open Society Foundations said in a statement. “In this climate of fear, falsehoods and rising authoritarianism, just voicing your views can draw death threats.”

Soros frequently donates to liberal causes. Conservative critics have accused him without evidence of secretly financing the caravan of migrants making their way toward the U.S.