New Jersey Gov. Chris Christie has fired a top aide and cut ties to another after it emerged his administration ordered traffic delays to exact political revenge. Documents released this week show Christie’s deputy chief of staff, Bridget Anne Kelly, personally ordered the closure of lanes leading to the George Washington Bridge, which connects New Jersey to New York City, to apparently punish the mayor of Fort Lee for declining to endorse Christie’s bid for re-election last year. At a lengthy news conference in Trenton, Christie apologized and said his aides had deceived him.

Gov. Chris Christie: “I come out here today to apologize to the people of New Jersey. I apologize to the people of Fort Lee, and I apologize to the members of the state Legislature. I am embarrassed and humiliated by the conduct of some of the people on my team. There’s no doubt in my mind that the conduct that they exhibited is completely unacceptable and showed a lack of respect for their appropriate role at government and for the people that we’re trusted to serve.”

In addition to firing Kelly, Christie has severed links to a longtime political adviser, Bill Stepien. Another Christie appointee, a high school friend of the governor named David Wildstein, appeared before a State Assembly panel on Thursday, but invoked his Fifth Amendment right to avoid self-incrimination. The U.S. attorney in New Jersey meanwhile has announced an inquiry into the traffic closures. Later in the day, Christie visited Fort Lee to personally apologize to local residents and Mayor Mark Sokolich. The scandal could threaten Christie’s expected candidacy for the Republican presidential nomination in 2016. Critics say that even if Christie was kept in the dark, the targeting of Fort Lee reflects a culture of intimidation encouraged under his watch.