Chaos broke out Monday at the Spirit Airlines terminal at Fort Lauderdale, FL Airport after a disruption in flights caused hundreds of travelers to remain stranded at the airport, according to NBC affiliate WTVJ.

Cell phone video posted to Twitter showed people crowding the ticket counters, many of them visibly upset.

Spirit said the backlog was caused by a lack of crews. The Florida-based company filed a lawsuit Monday against the Airline Pilots Association , International (ALPA), the ALPA Master Executive Council of Spirit pilots over the disruption.

“We are disappointed that ALPA has decided to engage in this unlawful slowdown,” said Paul Berry, spokesman for Spirit Airlines. “This has led to canceled flights and prevented our customers from taking their planned travel, all for the sole purpose of influencing current labor negotiations. So we reluctantly filed this suit to protect our customers’ and our operations.”

Some travelers had been stuck at the airport for several hours.