The United States views a car bomb that failed to go off in New York's Times Square as a potential terrorist attack, Reuters quoted Homeland Security Secretary Janet Napolitano as saying on Sunday. Police tipped off by a street vendor found and defused the bomb inside a sport utility vehicle in the business, shopping and entertainment area of Midtown Manhattan when it was packed with tourists and theater-goers on a warm Saturday evening. "We're taking this very seriously," Napolitano told CNN's "State of the Union" program. "We're treating it as if it could be a potential terrorist attack." Police said no motive or suspect had been identified. Napolitano and other officials have not specified whether the suspects are Americans or foreigners. Authorities said the failed bomb -- made of propane, gasoline and fireworks -- could have killed many people. "This wasn't make believe. This wasn't a false alarm. This was the real deal -- to hurt people," said Fire Commissioner Sal Cassano, adding the force of the bomb could have taken down the front of a building if it had gone off. New York has been on high alert for an attack since the Sept. 11 attacks in 2001 in which hijacked airliners toppled the World Trade Center's twin towers, killing thousands of people. NO IDEA WHO OR WHY New York Mayor Michael Bloomberg told an early morning news conference: "We have no idea who did this or why." Times Square was evacuated but most of it was reopened to vehicles and pedestrians shortly after 5 a.m. (0900 GMT) on Sunday. -- SPA