From TMZ:
"We've learned Danielle Bregoli and her mom were boarding a Spirit Airlines flight out of LAX Monday evening ... when Mom got into a dispute with a female passenger. We're told Danielle's mother was struggling to put her carry-on bag in the overhead, because she's wearing a walking cast for an injured foot ... and the wait wasn't sitting well with the third party.
Danielle says the other woman put her hands on her mom's throat, and that's why she had to "cold-cock" the impatient passenger.
After Danielle uncorked the punch, the woman made a citizen's arrest. A short time later police arrived and took all 3 off the plane. We're told no one wanted to press charges so there were no arrests and everyone involved decided their lawyers would handle it from here."
TMZ also says that Spirit Airlines has banned Bregoli and her mom from the airline for life.