A Lufthansa flight that left San Francisco Thursday morning was forced to make an emergency stop in Boston after a passenger attacked a fellow traveler mid-flight and had to be handcuffed to their seat — disrupting a transatlantic journey for more than 500 people.

The diversion of Flight 459 — an Airbus A380 carrying 508 passengers from SFO to Munich — drew Massachusetts State Police to Boston Logan International Airport and resulted in the passenger's arrest. It is the latest in a string of in-flight disruptions on long-haul international routes, and a reminder that air travel's most serious incidents often begin at Bay Area gates.

Lufthansa Flight 459 was roughly en route across the United States early Thursday when the trouble began. Massachusetts State Police said they were notified around 8 a.m. of a disturbance aboard the aircraft. According to police, a passenger attacked another passenger and had to be physically restrained and handcuffed to their seat before the crew declared the flight needed to divert.

The plane, a double-deck Airbus A380 — one of the largest commercial aircraft in regular service — landed at Boston Logan International Airport. There, state troopers took the passenger into custody and removed their luggage from the aircraft before it could continue. Police said Thursday they were not certain whether anyone had been injured and that the incident remained under active investigation.

Lufthansa confirmed the diversion in a statement, saying the flight had been forced to make "an unscheduled stop" in Boston because of "an unruly passenger who posed a threat to the safe continuation of the flight." The airline added that "the safety of all passengers and crew on board is always Lufthansa's top priority," but declined to elaborate on the specifics of the incident, saying only: "Please understand that we are unable to provide any further information regarding the incident."

After the passenger was removed and the aircraft refueled, Flight 459 continued on to Munich, with an estimated arrival time of 11:15 p.m. ET — several hours behind schedule. All 508 passengers remained aboard for the remainder of the journey.

The Airbus A380 that operates the SFO–Munich route is the same aircraft type involved in several high-profile incidents globally in recent years. At roughly 239 feet long with a capacity of up to 555 passengers in a standard configuration, the plane's sheer size makes any onboard disturbance a complex policing and logistics challenge: crews must manage the situation over hours of flight, and diversion decisions carry significant cost and delay implications for hundreds of travelers.

The identity of the arrested passenger has not been released. The Massachusetts State Police investigation is ongoing.