United Airlines CEO Jeff Smisek has resigned in light of an investigation that the U.S. attorney in New Jersey is conducting into possible influence peddling. Pictured: Smisek announces the merger Continental and United airlines, in New York City, May 3, 2010. Reuters

Amid an ongoing federal investigation, United Airlines announced that CEO Jeff Smisek and two other officials had stepped down, according to the New York Times. The airline named Oscar Munoz, chief operating officer for the railroad company CSX Transportation, as Smisek’s replacement.

Also leaving the company were Nene Foxhall, executive vice president for communications and government affairs, and Mark Anderson, senior vice president for corporate and government affairs.

The U.S. attorney in New Jersey is investigating the airline to see if it improperly tried to influence officials with the Port Authority of New York and New Jersey. United Airlines has already said it didn’t find any concerns relating to accounting or financial reporting during an internal investigation, according to the Wall Street Journal. Smisek is set to get $4.8 million in severance, among other forms of compensation.

“The departures announced today are in connection with the company’s previously disclosed internal investigation related to the federal investigation associated with the Port Authority of New York and New Jersey,” United Airlines said in a statement to the Times. “The investigations are ongoing and the company continues to cooperate with the government.”

The federal investigation associated with the Port Authority has investigators looking into United Airlines' relationship with David Samson, the former Port Authority head who resigned in 2014 and who had possible conflicts of interest while working there, Bloomberg Business reported. Investigators were looking for information regarding a series of United Airlines flights between Newark, New Jersey, and Columbia, South Carolina -- flights to a location where Samson’s wife had a home. The Port Authority runs Newark Liberty International Airport.

The flight route was canceled just days after Samson quit the Port Authority, which was then under scrutiny following the George Washington Bridge lane closure scandal of 2013, in which staff members of New Jersey Gov. Chris Christie were accused of deliberately closing traffic lanes on the bridge for political retribution, resulting in massive traffic gridlock.