WATCH: Fists Fly at Fort Lauderdale Airport After Airline Cancels Flights

On Monday, fights broke out between airline staff and angry passengers – and led to three arrests for inciting a riot, resisting arrest, trespassing and disorderly conduct.

“All of a sudden, one particular flight got canceled, and a mob ensued up here at the front counter, in front of everyone else who had been waiting in line,” a passenger told local station WSVN. “At that point, the ticket agents couldn’t handle what was going on, so they called in for the police.”

Passengers have also reported that they witnessed police brutality.

“Just witnessed police brutality at Fort Lauderdale airport @SpiritAirlines trying to get back to NYC … i'm tired its 2017,” witness and Twitter user Brionka Halbert wrote in a tweet with a video.

Earlier in the day, Spirit Airlines had cancelled at least seven flights after filing a lawsuit against their own pilot’s union, the Air Line Pilots Association (ALPA), over a new bargaining agreement. The airline claimed there was “an unlawful job action by Spirit pilots” and that the pilots have been “purposely and unlawfully disrupting the airline’s operations."

According to the lawsuit, the union has "engaged in a pervasive illegal work slowdown that has caused approximately 300 flight cancellations and has disrupted the travel plans of over 20,000 customers…. The Spirit pilots’ concerted refusal to accept junior assignments or pick up open time flying has dramatically impacted Spirit’s operations leading to cancellations throughout its system, and most particularly for flights departing from Fort Lauderdale, Chicago-O’Hare, Detroit, and Las Vegas."

“We are shocked and saddened to see the videos of what took place at Ft. Lauderdale-Hollywood International Airport this evening. This is a result of unlawful labor activity by some Spirit pilots designed to disrupt Spirit operations for our customers, by canceling multiple flights across our network,” Spirit Airlines spokesman Paul Berry told International Business Times.

“These pilots have put their quest for a new contract ahead of getting customers to their destinations and the safety of their fellow Spirit Team Members. It is for this reason, Spirit has filed suit in Federal Court to protect our customers' future travel,” Berry added.

The ALPA has denied the allegations, and told CBS News that the lawsuit is "unwarranted and counterproductive legal action."