When Lori Gabriel boarded a United Airlines flight from San Diego to Houston with her partner and his 4-year-old son, Braysen, she didn't expect the scene that was about to unfold.

Braysen, who is autistic, usually loves to fly. But shortly before takeoff, he wanted to take off his seatbelt and sit on the floor.

"It was impossible to restrain him," Gabriel told CNN. "He was fighting both me and his father. It took the both of us to try to get him back to his chair and get his seat belt back on. He started kicking, screaming and hitting."

"That's when a flight attendant came over and told us the flight couldn't take off until he's seated," she said. "I told her the boy has autism, we're trying, give us a minute."