New York Times Square returned to business as usual Friday as police investigating the explosion at a military recruiting center looked at dozens of security videotapes, hoping to identify the bicycle-riding bomber.
Among the videos was one showing a hooded cyclist pedaling toward an area where a bicycle was found ditched in the trash, and another with someone walking away from the same spot, police said.
Investigators suspect the bike - a 10-speed in good condition - may have been used by the bomber in the attack just before dawn Thursday on a landmark military recruiting station. Police released a photo of the blue bicycle on Friday, along with a picture from the video of the cyclist.
There were no injuries or serious damage from the bombing, which mirrored two previous small explosions at consulates in Manhattan.
"We're in the process now of identifying those cameras, downloading them," NYPD Commissioner Ray Kelly told CNN on Friday. "We've got a lot of cooperation from the businesses in the area, and we're doing the normal investigative steps that you would expect in a case like this."
Authorities said there was no connection between the blast and a letter sent to as many as 100 members of Congress bearing the words "Happy New Year, We Did It."
Officials said the lengthy anti-war letters - sent to congressional offices with photos of a man standing in front of the recruiting office before it was damaged - contained no threats.
Laura Eimiller, an FBI spokeswoman in Los Angeles, said agents questioned a Hollywood man about the letters to Congress and searched his home and concluded "there is no evidence linking the letters, which contained no threat, to the bombing."
A law enforcement official in Washington, who spoke on condition of anonymity because the investigation of the bombing was continuing, called the timing of the letters an "incredibly unbelievable coincidence" and said no charges were expected in connection with them.
Given the security process for Capitol mail, the letters probably were sent well ahead of the attack.
One law enforcement official said the "We Did It" referred to Democrats taking control of Congress in 2006.
The bomb, contained in a metal ammunition box, produced a sudden flash and billowing cloud of white smoke, and prompted a full-scale emergency response.
At Times Square on Friday, there were tourists snapping pictures, pedestrians bustling about - and a sense of firm resolve among the military people who were guarding the damaged recruiting station in the middle of a traffic island near the city's famed Theater District.
Jessica Lindsey, 30, of Pensacola, Fla., paused for pictures with friends in front of the recruiting station during their shopping expedition and birthday celebration.
"We were nervous about coming here and staying across the street," but hotel workers assured them everything was fine, she said.
The blast bears striking similarities to the two consulate explosions.
In October, two small explosive devices were tossed over a fence at the Mexican consulate, shattering some windows. Police said they believed someone on a bicycle threw the devices.
At the time, police said they were investigating whether it was connected to a nearly identical bombing at the British consulate on May 5, 2005. No one was arrested in either attack.
Those bombings involved dummy hand grenades packed with black powder as an explosive, Kelly said.