New York ramps up security ahead of marathon

On the heels of last week's deadly truck attack, New York city officials significantly increased security for Sunday's marathon, which was expected to attract tens of thousands of of competitors and spectators.

Along the 42-kilometre route, New York police deployed extra "blocking trucks" to protect against vehicle attacks, rooftop snipers, heavy weapons, dogs and helicopters.

"There will be two or three times as many people deployed. You'll have thousands of officers on duty this weekend," New York Governor Andrew Cuomo said on Saturday.

In addition, the state Police, National Guard and the Metropolitan Transportation Authority and the Port Authority of New York and New Jersey increased deployments at airports, bridges, tunnels, and mass transit systems before and after the race.

"I want to stress, this is just a precautionary measure. We have no information that points to any issues. This is just a precautionary measure, given recent events," Cuomo said.

Among the items that spectators were not allowed to bring: Suitcases and rolling bags, strollers, pets, folding camp chairs and non-transparent plastic bags.

More than 50,000 runners were registered to take to the streets before huge crowds of people cheering them on.

The marathon route connects all five of the city's boroughs, starting near the Verrazano-Narrows Bridge in Staten Island, snaking through Brooklyn, Queens and Manhattan, before circling up to the Bronx and back to Manhattan.

Sunday's race was not be the first time U.S. runners have had to worry about violence. Two brothers inspired by al-Qaeda killed three people and injured more than 260 with bombs at the finish line of the 2013 Boston Marathon.