A California Air National Guard Black Hawk helicopter crossed the path of a United Airlines flight headed towards John Wayne Airport in Orange County on Tuesday evening. 

The Federal Aviation Administration said United Airlines Flight 589 was approaching the airport around 8:40 p.m. when a Sikorsky Black Hawk helicopter “crossed in front” of the flight’s path. 

In a statement to CBS News, United Airlines said pilots were advised by air traffic control to watch for a military helicopter flying near the airport. The statement adds that the pilots saw the helicopter, received a traffic alert and leveled the aircraft. 

In a separate statement, the California Air National Guard said the helicopter, based out of Joint Forces Training Base Los Alamitos, was conducting a “routine training mission” when the incident occurred.  

“At the time, the aircraft was returning to Los Alamitos airfield along an established Visual Flight Rules (VFR) route at an assigned altitude while in communication with air traffic control,” the California Air National Guard said. “Both aircraft landed safely. A thorough review will be conducted in coordination with the appropriate agencies.”

The U.S. Army in its own statement said it was “aware of the incident involving a Black Hawk from the CA NG and is coordinating with the FAA to gather more details.”

According to air traffic control audio, the pilots told the tower controller that they received a resolution advisory, which is issued by the Traffic Alert and Collision Avoidance System. The alert is meant to notify the flight crew “that a vertical maneuver should, or in some cases should not, be performed to attain or maintain safe separation from a threat,” according to the FAA.

Before landing, the controller told the pilot that they would be addressing the situation because “that was not good.”

Pilots were able to land the plane safely around 8:49 p.m. United said the flight had 162 passengers and six crew members on board at the time of the incident. No injuries were reported.

The flight had departed from the San Francisco International Airport around 7:07 p.m. local time, according to information from Flightaware.com.

The FAA is continuing to investigate the situation.

This incident comes as the Department of Transportation has changed rules for helicopters flying around airports after recent close calls, including one at Burbank Airport. Controllers at the Los Angeles International Airport have also been limiting helicopter access around the area.  

This increased scrutiny also comes after a deadly mid-air collision in Washington, D.C., over the Potomac River last year, involving a U.S. Army Black Hawk helicopter and an American Airlines regional jet, which killed 67 people.