NEW YORK — Authorities on Friday were investigating whether an explosion at the Times Square military recruiting office was connected to strikingly similar bombings at two foreign consulates in New York, but ruled out a link to mysterious letters sent to Capitol Hill offices.
Investigators were also scrutinizing surveillance video and forensic evidence after a bicycle-riding bomber struck the landmark station Thursday, scarring one of the world's most recognizable locations.
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."
The lengthy anti-war letters — which arrived with photos of a man standing in front of the recruiting office before it was damaged — contained no threats, officials said.
Laura Eimiller, an FBI spokeswoman in Los Angeles, said an individual was questioned there about the letters to Congress and "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 is continuing, called the timing of the letters an "incredibly unbelievable coincidence" and said no charges were expected in connection with them.
Democratic lawmakers were startled to receive the letters in their office mail just hours after the early morning New York bombing, and turned them over to the Capitol Police.
One law enforcer said the "We did it" referred to the Democratic wins. The Democrats gained control of Congress in 2006.
Letters likely mailed well before bombing
In an e-mail to lawmakers, Capitol Police said the envelopes went through the standard security process. That process, which involves radiating incoming mail, can easily take a week or more, making it likely the letters were mailed well ahead of the bombing.
Law enforcement officials speculated the letters may have been sent to coincide with the fifth anniversary of the start of the Iraq war, which is March 19. And the "We did it" claim may simply be sarcasm connected to the war, one official said.
Each envelope was stamped with two $1 stamps and contained a white label with a return address, which the police did not identify in the e-mail. Police said the letters were safe and did not contain threats to lawmakers.
Video: Probe widens The man in the photo was thin with graying hair, wearing a striped flannel shirt and jeans, the Democratic aide said. A law enforcement official, who spoke on condition of anonymity because the case is ongoing, confirmed some of the contents of the letters as described by the aide.
The Associated Press obtained a copy of an e-mail sent from the office of Sen. Dianne Feinstein, D-Calif., to other lawmakers Thursday that reads:
"A few offices on the House side have received a letter today addressed to 'Members of Congress' with a picture of a man standing in front of the Times Square recruiting station that was bombed in New York today with the statement 'We did it.' He is standing in front of it with his arms spread out and he's attached his political manifesto."
No one injured in blast
The small bomb caused minor damage to the New York military recruiting station before dawn Thursday and police were searching for a hooded bicyclist described by a witness and seen on a surveillance video pedaling away.
The blast left a gaping hole in the front window and shattered a glass door, twisting and blackening its metal frame. No one was hurt, but Police Commissioner Raymond Kelly said the device, though unsophisticated, could have caused "injury and even death."
Authorities were still trying to determine exactly what kind of device was used. When investigators went through the evidence, they found a metal ammunition box that is believed to have contained the explosive. It was being sent for testing. Kelly said the box was readily available in Army-Navy surplus stores.
'We will not tolerate such attacks'
Mayor Michael Bloomberg said the act “insults every one of our brave men and women in uniform stationed around the world.”
“Whoever the coward was that committed this disgraceful act on our city will be found and prosecuted to the full extent of the law,” said Bloomberg. “We will not tolerate such attacks.”
Though subway cars passed through the Times Square station without stopping in the early hours of the investigation, normal service was soon restored, with some delays.
The recruiting station, located on a traffic island surrounded by Broadway theaters and chain restaurants, has occasionally been the site of anti-war demonstrations, ranging from silent vigils to loud rallies.
In October 2005, a group of activists who call themselves the Granny Peace Brigade rallied there against the Iraq war. Eighteen activists, most of them grandmothers with several in their 80s and 90s, were later acquitted of disorderly conduct.
The recruiting station was renovated in 1999 to better fit into the flashy ambiance of Times Square, using neon tubing to give the glass and steel office a patriotic American flag motif. For a half century, the station was the armed forces’ busiest recruiting center. It has set national records for enlistment, averaging about 10,000 volunteers a year.
U.S. authorities also are checking whether several people stopped at the Canadian border are linked to an explosion that damaged a military recruiting station in New York, police said on Friday.
NBC News' Justice Correspondent Pete Williams, The Associated Press and Reuters contributed to this report.