LOS ANGELES (CBSLA.com/AP) — A Southwest Airlines jetliner on its way to San Francisco returned to Los Angeles International Airport shortly after takeoff because of a fight between passengers, officials said Monday.

FBI agents met the plane at the gate late Sunday and one person was removed from the Boeing 737, Southwest spokeswoman Melissa Ford told The Associated Press.

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The pilot of Flight 2010 decided to return to LAX because of a “rapidly escalating” situation that culminated in a “physical altercation by one person against another,” Ford said. She did not elaborate but said the two passengers involved were not traveling together.

The passenger removed from the flight was detained for questioning. No arrest was immediately made, but the investigation was underway, FBI spokeswoman Laura Eimiller said.

“The allegations involved the reported assault of a fellow passenger,” she added.

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Several passengers reported the incident on social media, including one passenger who tweeted she was aboard the flight when a male passenger seated behind the alleged victim became upset when she reclined her chair.

Sources also told CBS2’s Randy Paige that the flight arose after the female passenger reclined her seat and the male passenger objected.

The flight left LAX around 9:50 p.m. and returned to the airport about an hour later, Ford said. The captain declared an emergency to receive priority for landing, she said.

The remaining 136 passengers switched planes and departed again for San Francisco International Airport around 12:20 a.m Monday, Ford said.

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