A fire aboard a London-bound Virgin Atlantic flight forced the plane to make an emergency landing in Boston on Thursday.
Massachusetts State Police said the crew extinguished the fire, which a preliminary investigation says probably started with a phone charger that ignited in a passenger seat.
"Preliminary investigation suggests it is a battery pack consistent in appearance with an external phone charger," a police spokesman said.
All 217 passengers on Flight 138 from New York as well as the crew were safely evacuated after landing. One passenger refused treatment for a smoke-related complaint.
A Virgin Atlantic statement said the flight was bound for Heathrow Airport.
The airline said it was "currently investigating" what led to smoke appearing in the cabin.
"The safety and security of our customers and crew is always our top priority and we are currently investigating to fully understand the circumstances," a company spokeswoman said.
"We’d like to thank our customers for their patience as we work with them to provide local accommodation or to rebook alternative flights to their final destination."
It was the second emergency landing at Boston’s Logan International Airport on Thursday.
Earlier, an American Airlines jetliner from Chicago declared an emergency when a cockpit light indicated an unspecified potential mechanical problem as it approached the city, but the plane landed without incident.