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 on Saturday.

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 19-liter 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.

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. 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.

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 Taleban statement on a website commonly used by extremists said: "The Pakistani Taleban announces its responsibility for the New York attack in revenge for the two leaders Al-Baghdadi and Al-Muhajir and Muslim martyrs."

Al-Qaeda's Iraq leader Abu Ayyub Al-Masri - also known as Abu Hamza Al-Muhajir - and Abu Omar Al-Baghdadi, the purported head of its local affiliate, the Islamic State of Iraq, were killed last month.

But Kelly said there is no proof to back the claim. There is no way to determine at this time if the bomb attempt was of domestic or foreign origin, he added.

A T-shirt vendor and a handbag vendor alerted police at about 6:30 p.m. (2230 GMT) 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, said he noticed the car at around 6:30 p.m. and wondered who had left it there.

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.

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.