TRENTON - Gov. Christie says he knew nothing of a plan by some of his closest aides to create traffic jams as political payback to a town mayor.

Christie spoke for two hours at a packed news conference Thursday morning. The governor was forced to address the scandal that he had initially dismissed as nothing more than partisan politics.

He says he had "no knowledge or involvement in this issue in its planning or execution." He adds that he was stunned by the "abject stupidity that was shown." Nevertheless, he said, he was responsible for what happened.

Christie also said he was firing Deputy Chief of Staff Bridget Anne Kelly "because she lied" to him. Christie said he initially asked his staff if anyone had anything to do with the closures, and when no one came forward, he considered the matter closed.

On Wednesday, an email exchange between Kelly and other Christie appointees went public.

Kelly is the latest casualty in the widening George Washington Bridge lane closure scandal. Messages obtained by News 12 New Jersey yesterday show Kelly arranged traffic jams to punish the Fort Lee mayor, who didn't endorse Christie for re-election. 

"Time for some traffic problems in Fort Lee," Kelly wrote in August in a message to David Wildstein, a top Christie appointee on the Port Authority of New York and New Jersey.

A few weeks later, Wildstein closed two of three lanes connecting Fort Lee to the heavily traveled George Washington Bridge, which runs between New Jersey and New York City.

The governor's opponent in the November election, Barbara Buono, finds it hard to believe he could have been kept in the dark for so long. "He runs it like a paramilitary organization," Buono says. "That's why when he says he didn't know anything about this, I don't buy it."

"I am responsible for what happened," Christie says. "I am sad to report to the people of New Jersey that we fell short."