A car bomb left in Times Square made of easily purchased items, including alarm clocks and gasoline, could have sent a “significant fireball” hurtling through one of the world’s busiest tourist spots, police said Sunday as they searched for a man caught on film who might be linked to the failed attempt.

The incident, coming months after a foiled plot by Afghan immigrants to blow up New York subways, underscored the vulnerability of heavily policed Times Square, which since the Sept. 11, 2001, attacks has been under close watch by police and scores of surveillance cameras.

“We’re very lucky. We know we live in a dangerous world,” said Mayor Michael R. Bloomberg on Sunday, describing the incident as a “further reminder of the dangers we face.”

After a night that saw most of the theater district under lockdown, Times Square on Sunday was jammed again with tourists, street vendors and shoppers who seemed to view the incident as an unavoidable result of a perilous world.

“No matter what they say about safety, there’s no real safety,” said Fati Adam, who was in town for the day from neighboring Connecticut. “Even with all the police around, these things happen.”

“Look how busy the place is,” she added, glancing at the throngs of people jostling for space on the sidewalks beneath a blazing sun. “How can you police everything?”

Police are hoping that hours of footage from cameras positioned around Times Square — packed with major hotels, theaters, stores and office towers — will help identify the driver of the dark green Nissan Pathfinder that came to a stop on West 45th Street near Broadway at 6:28 p.m. Saturday.

Police Commissioner Raymond Kelly said one camera captured images of a man walking swiftly down Shubert Alley, about half a block from the SUV, glancing over his shoulder in a “furtive manner.” Police were searching for the man, described only as white and in his 40s.

Kelly said the man’s actions “could be perfectly innocent,” but he made clear that his mannerisms drew investigators’ attention as they watched the video.

Police also planned to meet with a tourist from Pennsylvania who filmed the policeman on horseback who first responded to calls of a suspicious vehicle. The tourist told police he might have video of the person who was driving the SUV.

An Islamist website on Sunday said the Pakistani Taliban had claimed responsibility for the bomb, but there was no independent confirmation of the claim, and Kelly said there was no evidence to support it.

A monitoring group later said the Pakistani Taliban released a video — apparently dated early April — of their leader promising an attack on major U.S. cities “in some days or a month.” The video did not specifically mention the New York bombing attempt..

IntelCenter, which keeps track of militant media messages, said the nearly nine-minute video appeared credible.

In a city notorious for its lack of parking, the SUV that glided to the curbside in the heart of Times Square on a traffic-choked Saturday night was bound to draw attention.

Within minutes, street vendors had become curious about the unattended vehicle with the tinted back windows. Duane Jackson left his handbag stall and trotted across West 45th Street to peer into its front windows, seeing keys dangling from the ignition.

Lance Orton, a T-shirt vendor, spotted smoke coming from the Pathfinder and alerted a policeman on horseback. In the ensuing minutes, fear spread through the crowds. A series of loud “pops” rang out from the Nissan. Smoke began pouring from the vehicle. People scrambled to get away.

“I ran like everybody else,” Jackson said.

Nobody was injured Saturday, and police quickly closed most of the area and brought in a robot to scour the vehicle for explosives.

Kelly said it was unclear why the bomb did not detonate as planned, but he said the Pathfinder concealed a lethal mix of plastic cans filled with gasoline, M-88 firecrackers, three propane tanks, two alarm clocks, wires and a 70-pound metal gun box holding bags of a material “granular in nature.”

Police later said the material was fertilizer, which in some forms can be used to make explosives, such as those used by Timothy McVeigh in the Oklahoma City bombing of April 1995 that killed 168 people. However, police said the fertilizer in the SUV was nonexplosive.

Still, Kelly said he was told that had the bomb gone off, “the vehicle itself would have at least been cut in half. We were lucky it didn’t detonate.”

FBI agent George Venizelos, speaking at a news conference Sunday, agreed: “A lot of lives were probably saved.”

Kelly said the license plate on the SUV did not match the vehicle but instead belonged with a vehicle traced back to a Connecticut junkyard.

The mayor described the Times Square bomb as “amateurish” in the immediate aftermath of the incident, and on Sunday, Bloomberg said there was no indication it was the work of an international terrorist group.

Other officials described it in more serious terms as the details of the car’s contents became known, and most agreed that the incident amounted to a form of terrorism, be it a homegrown lone wolf or someone acting on behalf of an international group such as Al Qaeda.

“We’re taking this very seriously,” Homeland Security Secretary Janet Napolitano said on CNN’s “State of the Union.” “We’re treating it as if it could be a potential terrorist attack.”

Times Square’s regulars and visitors appeared to take it in stride Sunday. The man who calls himself the Naked Cowboy, who wears only briefs and a cowboy hat while roller-skating through the tourist spot, had no shortage of giggling tourists posing for pictures with him.

Street vendors said that business was no worse than usual and that the drop in tourism caused by the recession and the eruption of a volcano in Iceland — which disrupted air travel — had created more problems than the failed bomb.

“You’re never even safe in your own kitchen. There’s always a butcher knife or a bread knife around,” said Jackson, dismissing the idea that the spot where he has worked as a vendor for the last six years might be too risky. “It’s the same here.”

Times Square appeared to have more uniformed officers on patrol than usual Sunday. The Associated Press reported that the Transportation Security Administration had increased random screenings of passengers on outbound flights along the East Coast, quoting an unidentified Homeland Security official.

tina.susman@latimes.com