Authorities in New York City are viewing security camera footage and examining other evidence to determine who may have tried to set off a car bomb in the Times Square entertainment district.

Police evacuated thousands of tourists and theater-goers from Times Square Saturday night, after a T-shirt vendor noticed a suspicious vehicle and alerted officers.

Mayor Michael Bloomberg said the green Nissan Pathfinder sport utility vehicle contained three propane tanks, fireworks, two gasoline containers, and two clocks with batteries. He said the device looked "amateurish," but could have caused a "very deadly event" had it exploded.

A police spokesman, Paul Browne, says the bomb appeared to have started to detonate, but malfunctioned.

Bomb experts carefully removed the vehicle, and police reopened Times Square after several hours.

Bloomberg said authorities do not know who planted the bomb or why. U.S. Homeland Security Secretary Janet Napolitano said officials are treating the incident as though it could have been an act of terrorism.

She said investigators are following leads that include fingerprints and possible video of the car earlier on Saturday evening.

Times Square is one of New York's main attractions, with theaters and restaurants that draw millions of tourists throughout the year.

The U.S. Department of Homeland Security did not raise the national threat level after the incident.

Some information for this report was provided by AP, AFP and Reuters.