An Air India plane traveling from India to London crashed within moments of takeoff on Thursday, killing 241 passengers and crew and more people on the ground.

The Boeing 787-8 Dreamliner, which took off from the city of Ahmedabad, in western India, plowed into a residential area, hitting a hospital complex and medical student hostel.

One passenger survived the disaster—a British national who was sitting in seat 11A and who later told family he had no idea how he walked away.

It is not yet clear what caused the crash, which Indian Prime Minister Narendra Modi described as “heartbreaking beyond words.”

Officials warned the death toll could rise in what was quickly described as one of the deadliest aviation disasters in India’s history.

Air India Flight AI171 departed Sardar Vallabhbhai Patel International Airport at 13:39 local time (08:09 GMT) and was due to touch down at London’s Gatwick Airport at 18:25 BST.