NEW YORK (Reuters) - New York Governor Andrew Cuomo ordered security tightened on mass transit and at airports, bridges, tunnels and other crucial transportation links following Thursday's deadly truck attack in Nice, France.

In New York City, extra police from the anti-terror force and other units of the New York City Police Department patrolled locations associated with the French government and heavily trafficked areas such as Times Square, Mayor Bill de Blasio said on Friday.

"We are absolutely on alert," de Blasio said on WNYC radio's Brian Lehrer show. He said there was no specific threat against New York.

New York State Police and a joint task force of soldiers, airmen, naval militia and National Guard deployed extra personnel to the New York City area in the hours after at least 84 people were killed at a Bastille Day celebration on the French Riviera, Cuomo said late on Thursday in a statement.

"New York stands united with France and all our allies in the face of terror," the governor said. "This is not only an attack on France, but an attack on democracy."

After learning of the attack, the New York City Police Department sent detectives already on assignment in Paris, Lyon and The Hague to Nice to help authorities and to gather intelligence to send home, New York City Police Commissioner Bill Bratton said on Friday.

"Overseas detectives were moved to Nice to provide as much assistance as possible," Bratton said.

Cuomo said the U.S. Department of Homeland Security was "on heightened alert, monitoring world events," and that its regional staff had been told to keep a heightened state of awareness at events with mass gatherings.

Using multiple blockades to secure the location of a major event is a lesson New York City learned from watching past events around the world, de Blasio said on the live radio show.

"Whether it was July 4th or New Year's Eve celebration, we extensively secure the area and put up lots of blockades to keep this kind of attack from happening. And we're certainly going to be doing that a lot as we go forward," de Blasio said.

New York City police officers stood guard on Friday outside the Consulate General of France on Manhattan's Upper East Side, where New Yorkers left flowers in memoriam for the people killed in Nice.

The Park Lane Hotel in Midtown Manhattan showed its support for France overnight by illuminating its exterior in the blue, white and red colors of the French flag.

(Reporting by Barbara Goldberg; Editing by Jonathan Oatis, Toni Reinhold)