WASHINGTON — Drone activity caused officials to close airspace over one of the United States’ most critical Air Force bases for almost four hours late Friday and early Saturday, according to a base spokesperson and a Notice to Airmen posted on a federal website.

Bob Purtiman, chief of public affairs for the 88th Air Base Wing at Wright-Patterson Air Force Base in Ohio, said that the airspace remained restricted for approximately four hours from late Friday into early Saturday, while authorities monitored the situation, CNN affiliate WHIO reported.

The drones, referred to as “small unmanned aerial systems,” were being monitored by base units, Purtiman told WHIO. “To date, installation leadership has determined none of the incursions impacted base residents, facilities or assets,” he said.

In a recording of the Wright-Patterson air traffic control tower during the incident, posted on YouTube by The War Zone, a controller tells an aircraft identified as “MedFlight 8” to “use extreme caution for heavy UAS movement on the base.” UAS is an acronym for “unmanned aircraft system.”

The controller can be heard in the audio, which the outlet said was shared by a reader, saying security forces are handling the situation and tells the flight that the base’s class D airspace – usually the area around an airport up to an altitude of 2,500 feet – will be closed.

CNN reached out to the Air Force for comment, but did not immediately hear back.

The Wright-Patterson activity comes amid a string of mysterious drone sightings, primarily in the Northeast, that have been raising alarms among residents and local officials alike.

Drone sightings have occurred near other military installations, including Picatinny Arsenal and Naval Weapons Station Earle in New Jersey, as well as critical infrastructure like reservoirs.

Drone activity near US military sites has also been seen overseas. In November, British air bases used by the US Air Force reported drone incursions. Officials confirmed the incursions did not affect residents or critical infrastructure, and an investigation into their origin is ongoing.

Officials have urged calm and emphasized there is no evidence suggesting the sightings pose a security threat.

Wright-Patterson, about five miles outside the city of Dayton, is home to critical US Air Force commands, including the Air Force Research Lab, which bills itself as looking for ways to counter “technological advancements (that) bring threats to our way of life,” according to a video on its website.

The undated video animation shows an image of a drone approaching what looks like a remote US military outpost.

Wright-Patterson is also home to Air Force Materiel Command, which “conducts research, development, test and evaluation, and provides acquisition management services and logistics support necessary to keep Air Force weapon systems ready for war,” the command’s website says.

The sprawling base also hosts the National Air and Space Intelligence Center, whose mission is “to discover and characterize air, space, missile, and cyber threats,” its website says, adding that it provides “unique collection, exploitation, and analytic capabilities not found elsewhere.”

Another key base tenant is the headquarters of the 655th Intelligence, Surveillance and Reconnaissance Group, which oversees 14 intelligence squadrons scattered the country.

The base is also home to the National Museum of the US Air Force, a massive facility which houses some of the most important aircraft in history, including Bockscar, the B-29 bomber that dropped the atomic bomb on Nagasaki, Japan.

In another nod to history, Wright-Patterson was home to the 1995 peace talks that resulted in the Dayton Peace Accords between Yugoslavia, Bosnia-Herzegovina and Croatia, which ended a three-and-half-year war in Bosnia.

The 8,000-acre base is one of the largest the Air Force maintains worldwide, with more than 38,000 military, civilian and contractor employees. It is also the largest single-site employer in the state of Ohio, according to the base’s website.

Officials are urging anyone who observes suspicious drone activity to report it to local law enforcement or security.

As drone activity has garnered significant media attention, former FBI Supervisory Special Agent Tom Adams suggested to CNN that recent sightings could be influenced by copycat behaviors due to heightened scrutiny and coverage of the issue.

“I think we’re looking at a few different things. First, I do believe that there are probably some legitimate visual drone sightings by alert residents and law enforcement in New Jersey,” Adams said on Friday.

Rob D’Amico, the former chief of the FBI counter-drone unit, told CNN that more than 90% of reported drone sightings are likely misidentified manned aircraft or natural objects, while the surge in drone activity is creating confusion and exposing critical gaps in airspace security.

“What you’re now seeing is people are starting to fly drones ... to either make more chaos or to look for their own drones,” D’Amico said. “They have to start telling the people and other government officials what they’re actually doing, what they’re seeing... the more transparency.”

Both the Department of Homeland Security and local law enforcement continue to investigate the reported sightings, striving to determine the nature of the aircraft involved. — CNN