New York Gov. Andrew Cuomo said security would be doubled at critical infrastructure points around the city.
He added that State Police are assisting Secret Service and other relevant federal and local authorities in the ongoing investigation.
"Out of an abundance of caution, I am deploying 100 additional National Guard soldiers and directing State law enforcement to double security at vital assets across New York, including LaGuardia and JFK, mass transit systems, and bridges and tunnels," said Cuomo.
Cuomo said the bridges and tunnels with stepped-up security include the Staten Island crossings, the George Washington, RFK, Verrazzano-Narrows, Bronx-Whitestone, Throgs Neck, Henry Hudson, Marine Parkway-Gil Hodges Memorial, Cross Bay Veterans Memorial and Mario M. Cuomo Bridges and the Lincoln, Holland, Hugh L. Carey and Queens Midtown Tunnels.
NYPD officers from the counter-terrorism bureau were also stationed outside Grand Central Terminal and other potential targets.
Authorities were also on high alert in Westchester County, where devices were found at the Bedford home of George Soros and the Chappaqua home of the Clintons.
Police officers are now assisting in the screening of mail at county office buildings, and a Westchester detective is embedded in the joint terrorism task force investigating all recent incidents. The county may be thought of as just a suburb, but officials say it is home to millionaires and billionaires, some whom are now are being targeted.
* More New York City news
* Send us a news tip
* Download the abc7NY app for breaking news alerts
* Follow us on YouTube