The U.S. government shutdown is hitting the nation’s airports.

The Federal Aviation Administration (FAA) briefly halted flights heading into New York‘s LaGuardia airport amid an air traffic controller staffing shortage. The halt was lifted but delays remain. Flights were also reportedly delayed in Newark, Philadelphia, Washington, D.C., and Jacksonville.

Yahoo Finance emailed two FAA officials and received automatic replies that the people were not working because of "the lapse of government funding.” Another spokesperson stated: “We have experienced a slight increase in sick leave at two facilities. We’ve mitigated the impact by augmenting staffing, rerouting traffic, and increasing spacing between aircraft when needed. The results have been minimal impacts to efficiency while maintaining consistent levels of safety in the national airspace system.”

An increasing amount of TSA employees are skipping work during the shutdown, citing financial constraints and an inability to work without being paid.

Sara Nelson, president of the Association of Flight Attendants-CWA, released a statement supporting the air traffic controllers:

"The aviation system depends on the safety professionals who make it run. They have been doing unbelievably heroic work even as they are betrayed by the government that employs them. They are fatigued, worried, and distracted - but they won't risk our safety. So the planes will stay on the ground," Nelson stated. "This is anything but a sick out - it is only about our safety and the air traffic controllers' absolute commitment to it.”

On Wednesday, the nation’s largest unions for pilots, flight attendants, and air traffic controllers said in a joint statement that “in our risk averse industry, we cannot even calculate the level of risk currently at play, nor predict the point at which the entire system will break. It is unprecedented.”

More from the statement: “Due to the shutdown, air traffic controllers, transportation security officers, safety inspectors, air marshals, federal law enforcement officers, FBI agents, and many other critical workers have been working without pay for over a month. Staffing in our air traffic control facilities is already at a 30-year low and controllers are only able to maintain the system’s efficiency and capacity by working overtime, including 10-hour days and 6-day workweeks at many of our nation’s busiest facilities.”