SEATAC, Wash. (AP) — Federal crews said there has been a dramatic increase in violent conduct at airports and on planes. The Federal Aviation Administration said the dangerous behavior doubled in the past month.

The FAA is investigating more than 2,500 cases of violence, KING5 reported. At least 1,900 of those cases involved a dispute over masks.

“I can say I’m not surprised. Honestly, I’m not surprised,” said Melinda Jorge Henderson, a flight attendant and Vice President of the Association of Flight Attendants Council 19.

Henderson said crews are seeing fistfights and verbal and physical assaults of flight attendants. She believes things may have gotten worse now that many airlines have reintroduced alcohol.

On Sunday, a Southwest Airlines flight attendant lost two teeth during an assault. In January, an Alaska Airlines passenger bound for Seattle shoved a flight attendant. That person is now facing a $15,000 fine.

Henderson believes the COVID-19 pandemic has brought things to a boiling point, and people don’t want to be told what to do.

“But unfortunately, if you’re traveling on public transportation, there are rules that apply to everybody, you know, even us as crew members,” said Henderson. “We all have to abide by rules.”

For Memorial Day weekend, Seattle-Tacoma International Airport expects to see 100,000 people daily. Travelers should expect longer lines, fewer empty seats, and mask requirements.