Authorities said Friday there was no link between a letter sent to several members of Congress that read "We did it" and the bombing of a military recruiting center in New York City's Times Square.

The person who wrote the letter is an anti-war activist and has been questioned in the Los Angeles area, law enforcement officials told The Associated Press. The man sent up to 100 letters to various people in Congress and even mailed a photo of a man standing in front of the Times Square office.

"It was just an incredibly unbelievable coincidence," said one of the law enforcement officials, who spoke on condition of anonymity because the investigation in New York is continuing.

Authorities on Thursday questioned the Los Angeles area man who sent the letters, but found his mailings to be unrelated to the bombing and did not expect to bring any charges, the officials said.

Democratic lawmakers on Capitol Hill were startled to receive the letters in their office mail Thursday afternoon, just hours after the early morning New York bombing, and turned them over to the Capitol Police.

Congressional sources told FOX News that the letters that showed up at the House offices may not have gone through the U.S. Mail and instead were possibly dropped off in person at internal mail pick-up sites inside the Capitol complex and office buildings, where they would have been screened and delivered to Congressional offices.

In a phone interview with WNYW-TV in New York, the top Republican on the House Homeland Security Committee, Rep. Pete King (R-NY), said more letters could be discovered Friday morning.

"They are expecting quite a few more to be received because I understand there are numbers inside of the letters that indicates there could have been up to 100 of them that have been sent," said King.

Return addresses on the manila envelopes delivered to Congressional offices reportedly point to a Hollywood Hills origin.

A federal law enforcement source confirmed that the FBI has been looking into a person of interest in Los Angeles; however, no arrest has been made.

WNBC reported Thursday night that authorities were revisiting a recent incident along the Canadian border that may be connected to the bombing.

The incident last month involved four men who tried to flee the checkpoint when Canadian officials attempted to question them at the border, an investigator told WNBC.

The station reported that two of the men got away. The men left behind a backpack that included photos of locations in New York City, including the recruitment center at Times Square, sources told WNBC.

Police sources also say the letters on Capitol Hill are not connected to The New York Times Square bombing.

The manila envelopes sent to Congressional offices Thursday contained a photo of a man standing in front of the Times Square military recruiting station, according to a Democratic aide who spoke on condition of anonymity because the matter is under investigation. The photo was the kind commonly sent as a holiday greeting card.

The message on the card: "Happy New Year, We Did It."

The envelope also contained a packet of approximately 10 sheets of paper that seemed to be a political manifesto railing against the Iraq war and a booklet. The aide didn't know what the booklet was.

The letter was sent to at least eight congressional offices.

Postal inspectors were at the Capitol Thursday investigating the letters alongside Capitol Police, U.S. Postal Inspection Service spokesman Douglas Bem said. He had no details about the letters' content. A second law enforcement official, who spoke on condition of anonymity because the case is ongoing, confirmed some of their contents as described by the Democratic aide.

FOX News has learned that the offices of Reps. Hilda Solis, D-Calif., John Tierney, D-Mass., and Lois Capps, D-Calif., received the letters.

There is some speculation on Capitol Hill that members of the Out of Iraq Caucus may be the targets of the letter. Solis, Tierney and Capps are three of the more than 70 members of that caucus.

The Associated Press obtained a copy of an e-mail 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."

The man in the photo was thin, white with graying hair, wearing a striped flannel shirt and jeans, according to the Democratic aide.

The letters were screened by security officers and determined to be safe. None contained threats to lawmakers, Capitol Police said in an e-mail to Capitol Hill offices.

Police urged anybody who receives the letter to immediately contact authorities and not handle the package.

Capitol Police said in the message that the envelopes were stamped with two $1 stamps and contained a white label with a return address, which the police did not identify. Police have not yet established a connection between the letters and the New York bombing.

Sources tell FOX News that it's believed that at least a couple of the letters did not bear postmarks.

There is no indication that letters were sent to any members of the U.S. Senate. A spokesman for New York Sen. Hillary Clinton said her office did not receive the letter.

The small bomb caused minor damage to the New York military recruiting station before dawn Thursday and police were searching for a hooded bicyclist seen on a surveillance video pedaling away.

Click here for more on the bicyclist caught on surveillance video.

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."

FOX News' Chad Pergram, Trish Turner and The Associated Press contributed to this report.