NEW YORK -- Police investigating a terror attack that could have set off a deadly fireball in Times Square focused Sunday on finding a man who was videotaped shedding his shirt near the SUV where the bomb was found.

Police said the gasoline-and- propane bomb was crude but could have sprayed shrapnel and metal parts with enough force to kill pedestrians and knock out windows on one of America's busiest streets, full of Broadway theaters and restaurants on a Saturday night.

A large amount of fertilizer riggedwith wires and fireworks were found with the bomb, but police said it was not the ammonium nitrate-grade that can explode.

The surveillance video shows an unidentified white man who appeared to be in his 40s slipping down an alley and taking off a shirt, revealing another underneath. In the same clip, he's seen looking back in the direction of the smoking vehicle and furtively putting the first shirt in a bag, Police Commissioner Raymond Kelly said.

The homemade bomb was made largely with ordinary items, including three barbecue-grill-size propane tanks, two 5-gallon gasoline containers, store-bought fireworks and cheap alarm clocks attached to wires.

"The intent of whoever did this was to cause mayhem, create casualties," Kelly said.

Authorities didn't know how deadly the bomb could have been, how it failed or who was responsible.

Police already had identified the registered owner of the 1993 Nissan Pathfinder, which didn't have an easily visible vehicle identification number and had license plates from another car, and were looking to interview him. Police also were searching more video, thought to be in the possession of a Pennsylvania tourist, of the man in the alley.

The bomb at Times Square, one of the flashiest and best-known places on Earth, was found at the height of dinner hour before theatergoers headed to Saturday night shows.

Timers were connected to a 16-ounce can filled with fireworks, which apparently were intended to set the gas cans and propane afire, Kelly said.

He said the bomb "looks like it would have caused a significant fireball" had it fully detonated. He said the vehicle would have been "cut in half" by an explosion and people nearby could have been sprayed by shrapnel and killed.

Police had feared that another component -- a metal rifle cabinet packed with more than 100 pounds of a fertilizer-like substance and rigged with wires and more fireworks -- could have made the device even more devastating. Test results late Sunday showed that it was indeed fertilizer -- but not a type volatile enough to explode like the ammonium nitrate-grade fertilizer used in previous terror attacks, said police spokesman Paul Browne.

The New York Police Department and FBI were examining "hundreds of hours" of security videotape from around Times Square, Kelly said.

Police released a photograph of the SUV, a dark-colored Nissan Pathfinder, as it crossed an intersection at 6:28 p.m. Saturday. A vendor pointed the SUV out to an officer about two minutes later.

The license plate found on the vehicle did not belong to the SUV; police said it came from a car found in a repair shop in Connecticut.

Duane Jackson, a 58-year-old handbag vendor from Buchanan, N.Y., said he noticed the car and wondered who had left it there in a no-standing zone.

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.

They were looking in the car "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.

The Pakistani Taliban claimed responsibility in a video posted on the Internet on Sunday, according to the SITE Intelligence Group. SITE, a U.S.-based terrorist tracking organization, first uncovered the video on YouTube; it later appeared to have been removed from the website.

If the claim is genuine, it would be the first time the Pakistani Taliban has struck outside of South Asia. It has no known global infrastructure like al-Qaida.