Southwest Airlines reported that a jetliner making a flight to San Francisco on Sunday was forced to return to Los Angeles International Airport due to a fight between two passengers.

Southwest flight 2010 returned to LAX after the pilot declared an emergency following a "rapidly escalating" situation that culminated in a "physical altercation by one person against another," said spokeswoman Melissa Ford, according to the Associated Press. She declined to elaborate, but said the two passengers involved weren't traveling together.

One witness claimed the man was harassing a woman about a reclining chair, reported ABC's California associate KFSN-TV.

FBI agents met the plane at the gate late Sunday and detained the man from the Boeing 737. The man was questioned and later released, however the FBI admitted they still need to do more interviews for their investigation, according to CBS Los Angeles.

The remaining 136 passengers switched planes and departed again for San Francisco International Airport two hours later, arriving about five hours behind schedule.