Two Southwest Airlines flight attendants are being treated for injuries after a passenger jet heading to Las Vegas from Southern California took a dramatic plunge shortly after take-off on Friday in response to an alert about a nearby plane, the airline and passengers said.

Southwest flight 1496 was responding to an onboard alert about another aircraft in its vicinity, the Federal Aviation Administration said. The FAA is investigating.

The crew responded to two air alerts that required the pilot to climb then descend, the airline said in a statement.

The flight departed from Hollywood Burbank Airport just before noon.

Passengers posted on social media that the plane took a dramatic drop soon after take-off.

“Pilot said his collision warning went off & he needed to avoid plane coming at us,” comedian Jimmy Dore posted on X.

The plane was not in the immediate vicinity of the Hollywood Burbank Airport, north of Los Angeles, at the time, said Mike Christensen, an airport spokesman.

Christensen said that neither the control tower or the operations department, which tracks planes departing and arriving, have any record of the Southwest flight plunging in their airspace.

Southwest said the flight continued to Las Vegas, “where it landed uneventfully.”

The airline said that it is working with the Federal Aviation Administration “to further understand the circumstances” of the event.