Two flight attendants were injured on a Southwest Airlines flight taking off in Burbank, Calif. after the plane made several sudden altitude changes to avoid colliding with another aircraft.

CNN reported that the Las Vegas-bound flight made a sudden drop of 475 feet in order to avoid a privately owned Hawker Hunter fighter jet. The commercial jet then climbed about 600 feet in about a minute.

The extent of the injuries were not disclosed.

“Southwest is engaged with the Federal Aviation Administration to further understand the circumstances,” the airline said in a statement to NewsNation. “Nothing is more important to Southwest than the Safety of our Customers and Employees.”

The Federal Aviation Administration said in a statement that it was investigating the incident and that it was in contact with the airline.

Most commercial planes are equipped with an alert system to avoid collisions that can direct pilots to climb or descend rapidly.

The avoided collision comes less than a week after a SkyWest Airlines plane made what the pilot called an “aggressive maneuver” during landing in North Dakota to avoid a B-52 bomber.

In January, an American Airlines flight collided with an Army helicopter during a training exercise above the Potomac River, killing 67 people. The FAA has since modified helicopter routes in and around Washington Reagan National Airport, some of the most complex and restricted airspace in the country.