A source tells ABC News one passenger accused another passenger of having a firearm, but when the aircraft was swept and passengers re-screened, no weapon was found. According to another source with knowledge of the investigation, the passenger reported to have a firearm was detained, but authorities later discovered he did not have a weapon on him. The man had a history of mental illness, the source said.
The Embraer 170 aircraft was was en route to Los Angeles International Airport from San Antonio, Texas, according to the FAA.
The FBI's Phoenix office said it was investigating the incident, but said there was no threat to public safety. They declined to tell ABC News if the suspect was in jail, a hospital, or has been released as of Thursday morning.
The FAA identified the aircraft as Compass flight 5720; it landed without incident at 4:35 p.m. PT.
One the passengers on the plane, Ryan Healy, tweeted a series of photos, video and posts detailing how FBI agents entered the plane's cabin and removed the individual, and how the plane was escorted by fighter jets.
Tucson Airport sent out a series of tweets, beginning at 5:37 p.m., the first of which read, "There was an incident on a flight was a diverted to @tucsonairport. 1 suspect detained at this time. Aircraft deemed safe."
Two minutes later, Tucscon Airport tweeted, Passengers on diverted flight @tucsonairport and are being transported to terminal for rescreening."
A subsequent tweet, only a minute later, classified the diversion to Tucson Airport as a result of "interference with flight crew."
Less than half an hour after its first tweet, Tucson Airport said "Passengers are currently being re-screened. They will then continue on to their final destination."
ABC News' Joshua Hoyos, James Meeks, Jonah Lustig and Erin Dooley contributed to this report.