Police found an "amateurish" but potentially powerful bomb that apparently began to detonate but did not explode in a smoking sport utility vehicle in Times Square, authorities said Sunday.
Thousands of tourists were cleared from the streets for 10 hours after two vendors alerted police to the suspicious vehicle, which contained three propane tanks, fireworks, two filled 5-gallon gasoline containers, and two clocks with batteries, electrical wire and other components, Police Commissioner Raymond Kelly said.
"We avoided what could have been a very deadly event," Mayor Michael Bloomberg said. "It certainly could have exploded and had a pretty big fire and a decent amount of explosive impact."
The bomb appeared to be starting to detonate but malfunctioned, top police spokesman Paul Browne said Sunday. Firefighters and witnesses said they heard a popping sound from inside the vehicle.
Bloomberg called the explosive device "amateurish" but potentially deadly, noting: "We are very lucky."
The NYPD bomb squad "has seen sophisticated devices before and they described this one as crude," Browne said. "But it was nevertheless lethal." If detonated properly, it could have created a large fireball and sprayed shrapnel -- metal from the propane tanks and car parts -- that could have killed pedestrians in the immediate vicinity, Browne said.
Police on Sunday were trying to determine whether a gun locker also discovered in the vehicle was part of the threat.
The metal storage cabinet for rifles weighed roughly 200 pounds, causing suspicion it could contain more powerful explosives meant to be detonated by the fireball, Browne said. Investigators had isolated the locker at a police firing range in the Bronx and were trying to open it remotely to determine what's inside.
No suspects were in custody, though Kelly said a surveillance video showed the car driving west on 45th Street before it parked between Seventh and Eighth avenues. Police were looking for more video from office buildings that weren't open at the time.
Homeland Security Secretary Janet Napolitano said on NBC's "Meet the Press" that officials are treating the incident as a potential terrorist attack. The mayor said earlier Sunday that "we have no idea who did this or why" but said pointed out that the city is a frequent target of terrorism.
"These things invariably ... come back to New York," Bloomberg said.
A T-shirt vendor and a handbag vendor alerted police at about 6:30 p.m, the height of dinner hour before theatergoers head to Saturday night shows.
Smoke was coming from the back of the dark-colored Pathfinder, its hazard lights were on and "it was just sitting there," said Rallis Gialaboukis, 37, another vendor who has hawked his wares for 20 years across the street.
Duane Jackson, a 58-year-old handbag vendor from Buchanan, N.Y., said he noticed the car at around 6:30 p.m. and wondered who had left it there.
"That was my first thought: Who sat this car here?" Jackson said Sunday.
Jackson said he looked in the car and saw keys in the ignition with 19 or 20 keys on a ring.
He said he alerted a passing mounted police officer.
"That's when the smoke started coming out and then we heard the little pop pop pop like firecrackers going out and that's when everybody scattered and ran back," he said.
"Now that I saw the propane tanks and the gasoline, what if that would have ignited?" Jackson said. "I'm less than 8 feet away from the car. We dodged a bullet here."
He didn't think the car had been there for more than 10 or 15 minutes.
A white robotic police arm broke windows of the SUV to remove any explosive materials. A Connecticut license plate on the vehicle did not match up, Bloomberg said. Police interviewed the Connecticut car owner, who told them he had sent the plates to a nearby junkyard, Bloomberg said.
The SUV was towed early Sunday to a forensic lab in Queens, where it was being "thoroughly checked for prints, hairs and fibers," Browne said Sunday. Napolitano said fingerprints had been recovered from the vehicle.
Heavily armed police and emergency vehicles shut down the city's busiest streets, choked with taxis and people on one of the first summer-like days of the year. Times Square lies about four traffic-choked miles north of where terrorists bombed the World Trade Center in 1993, then laid waste to it on Sept. 11, 2001.
The car was parked on one of the prime blocks for Broadway shows, with seven theaters housing such big shows as "The Lion King" and "Billy Elliot."
The curtain at "God of Carnage" and "Red" opened a half-hour later than usual, but the shows were not canceled, said spokesman Adrian Bryan-Brown.
Part of a Marriott hotel was evacuated for hours, unnerving thousands of tourists attending Broadway show, museums and other city sights.
Melissa Williams and Crysta Salinas returned from a visit to a King Tut exhibit near Times Square to find themselves out of their hotel room until 2 a.m. They sat in a deli until they could get into their room.
"No more New York," said Salinas, 28, from Houston.
"We went to two Broadway shows, we went to the museum, we did everything we wanted to do this time, so we're not going to do this again," said Williams, 56, from Houston.
Bloomberg left early from the White House correspondent's dinner Saturday night. President Barack Obama, who attended the annual gala, praised the quick response by the New York Police Department, White House spokesman Nick Shapiro said.
The FBI Joint Terrorism Task Force in New York responded along with the NYPD, said agent Richard Kolko.
Top federal law enforcement and intelligence officials -- Obama's national security adviser James Jones, national intelligence director Dennis Blair, CIA chief Leon Panetta, Napolitano and Attorney General Eric Holder -- planned to participate in a meeting later Sunday on the bomb.
The latest terror threat in New York came last fall when air shuttle driver Najibullah Zazi admitted to a foiled homemade bomb plot aimed at the city subway system.
The theater district in London was the target of a propane bomb attack in 2007. No one was injured when police discovered two Mercedes loaded with nails packed around canisters of propane and gasoline.
Officials said the device found Saturday was crudely constructed, but Islamic militants have used propane and compressed gas for years to enhance the force of explosives. Those instances include the 1983 suicide attack on the U.S. Marines barracks at the Beirut airport that killed 241 U.S. service members, and the 2007 attack on the international airport in Glasgow, Scotland.
In 2007, the U.S. military announced that an al-Qaida front group was using propane to rig car bombs in Iraq.
Times Square has been a frequent target, if not for potential terrorists, then for rabble-rousers.
In December, a parked van without license plates led police to block off part of the area for about two hours. A police robot examined the vehicle, and clothes, racks and scarves were found inside.
In March 2008, a hooded bicyclist hurled an explosive device at a military recruiting center, producing a flash, smoke and full-scale emergency response. No suspect was ever identified.
Police have spent years trying to crack down on street hustlers and peddlers preying on tourists. But there have been two major gunfights in recent months. A street hustler armed with a machine pistol exchanged shots in December, shattering a Broadway theater ticket window, before police fatally shot him.
Four shootings and more than 50 arrests on a mile-long stretch of Manhattan last month around Times Square prompted the mayor to call the mayhem "wilding."
Contributing to this report were Associated Press writers Cristian Salazar, Michael Kuchwara and AP Radio correspondent Julie Walker in New York, AP Washington bureau chief Ron Fournier, AP writers Eileen Sullivan, Pete Yost and Kimberly Dozier in Washington, Colleen Long in North Carolina and Robert H. Reid in Kabul.