The King has said he and the Queen are "desperately shocked by the terrible events" of the Air India crash in Ahmedabad, and expressed his "deepest possible sympathy".
Charles, 76, added: "Our special prayers and deepest possible sympathy are with the families and friends of all those affected by this appallingly tragic incident across so many nations, as they await news of their loved ones.
"I would like to pay a particular tribute to the heroic efforts of the emergency services and all those providing help and support at this most heartbreaking and traumatic time."
A London-bound Air India plane carrying 242 people crashed shortly after take-off at 13:38 local time (09:08 BST) in Ahmedabad, western India. The plane came down in a residential area, reportedly near a doctors' hostel.
Many people are feared to have been killed onboard on the aircraft, which appeared to explode when it crashed.
A video of the incident, obtained by local media, shows the Air India aircraft flying over a residential area before crashing, creating what appears to be a huge fireball followed by large plumes of black smoke.
Statement from the Airline
In a statement on X, Air India said: "Air India confirms that flight AI171, from Ahmedabad to London Gatwick, was involved in an accident today after take-off. The flight, which departed from Ahmedabad at 1338 hrs, was carrying 242 passengers and crew members on board the Boeing 787-8 aircraft.
"Of these, 169 are Indian nationals, 53 are British nationals, 1 Canadian national and 7 Portuguese nationals. The injured are being taken to the nearest hospitals.
"We have also set up a dedicated passenger hotline number 1800 5691 444 to provide more information. Air India is giving its full cooperation to the authorities investigating this incident."
Prime Minister reacts
UK Prime Minster Sir Keir Starmer said the scenes emerging from Ahmedabad were "devastating".
"I am being kept updated as the situation develops, and my thoughts are with the passengers and their families at this deeply distressing time," he said.
Foreign Secretary David Lammy said the UK was working with local authorities in India to "urgently establish the facts" and provide support.