This still photo released by the New York City Police Department, Sunday, May 2, 2010, shows one of the alarm clocks found in the Nissan Pathfinder that was used in the attempted attack on Times Square on Saturday evening, May 1, 2010.
(AP Photo/New York Police Department)

Associated Press Writers

By TOM HAYS and DEEPTI HAJELA

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.

The bomb "looks like it would have caused a significant fireball" had it fully detonated, police Commissioner Ray Kelly said.

A large amount of fertilizer rigged with wires and fireworks was 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 apparently 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, 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.

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

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