As travel rates begin to increase, the Transportation Security Administration is reporting a rise in unruly passengers – including one in Denver who allegedly bit two TSA agents this month.

In a release Thursday, TSA said a passenger allegedly bit the agents at Denver International Airport earlier in June. The agency did not release any information about what led to the incident but said it remains under investigation.

The passenger faces a potential civil fine of up to $13,910 for each violation of airport security requirements, the agency said.

This incident, and another in Louisville, Kentucky, this month triggered law enforcement involvement. In Louisville, a passenger alleged assaulted two TSA agents while trying to leave the exit lane, the agency said.

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That passenger is facing the civil fine, in addition to state charges for criminal trespass, fleeing and evading police, misdemeanor assault and resisting arrest. No charges have been announced against the Denver passenger as of Thursday.

“Passengers do not arrive at an airport or board a plane with the intent of becoming unruly or violent,” said Darby LaJoye with TSA. “However, what is an exciting return to travel for some may be a more difficult experience for others, which can lead to unexpected, and unacceptable, behaviors.”

There have been at least 69 incidents in which TSA employees have been assaulted since March 1, 2020, according to TSA.

The Federal Aviation Administration has also reported more than 3,000 incidents involving unruly passengers in 2021, with 487 investigations launched. In 2020, there were only 183 investigations launched and, in 2019, there were 146.

LaJoye said these kinds of incidents needlessly interrupt travel, delay flights and other transportation operations across the country.

TSA is urging travelers to be patient when they travel. TSA is also taking steps to deter assaults against officers and flight crew, including beginning flight crew self-defense training in July, led by the federal air marshals.

Passengers with questions about checkpoint procedures and how to prepare for TSA security screenings should contact TSA Cares at 855-787-2227 (Federal Relay 711).