American Airlines Group Inc. said a flight from New York to John Wayne Airport in Orange County, California, diverted to Denver after a male passenger “physically assaulted” a flight attendant.

Flight 976 landed safely and authorities detained the individual, the airline said in a statement. American banned the passenger for life and said it’s working with local law enforcement and the Federal Bureau of Investigation.

“Acts of violence against our team members will not be tolerated,” American said. “This behavior must stop, and aggressive enforcement and prosecution of the law is the best deterrent.”

The Federal Aviation Administration said it’s also investigating what it called “a passenger disturbance.” It said in a statement that the flight—an Airbus SE 321 out of John F. Kennedy International Airport in New York—landed at Denver International Airport without incident at 6:37 p.m. local time.