Up to 16 people were treated by medics in Ireland after a transatlantic flight hit unexpected and severe turbulence hundreds of miles from shore.
The US airline said it was providing care and support to those on board.
It said 10 customers and two flight attendants were taken to University Hospital Limerick and all were discharged except for one flight attendant who received further treatment.
"United Airlines is providing care and support to customers and crew of flight UA880 which experienced severe and unexpected turbulence during a flight from Houston to London Heathrow," a spokesman said.
Passengers took to social media to describe the incident with one calling the scenes pure chaos and another saying she thought she might die.
It is understood other passengers were assessed by paramedics and ambulance crews which met the plane on the runway after it landed at 5.55am.
The plane was in the air for two and a half hours after the incident occurred over the Atlantic and the alarm was raised with Irish air traffic control staff at 3.20am.
There were 207 passengers on the Boeing 767-300 and 13 crew including three pilots in the cockpit.
Most of them remained at Shannon Airport until another plane was arranged to fly them on the final stretch of the journey to Heathrow just after midday.
The Irish Aviation Authority (IAA) said the incident would be investigated.
It said the flight travelled through "unexpected turbulence" which led to passengers and crew being injured before the pilot diverted the plane to Ireland.
"Shannon air traffic control facilitated the flight diversion and the aircraft landed safely," a spokesman for the IAA said.