An Air India passenger plane bound for London's Gatwick airport crashed shortly after taking off in Ahmedabad, western India, on Thursday, killing 241 passengers and crew.
It later emerged that only one passenger, a British man, had survived.
Among those on board were Indian, British, Portuguese and Canadian nationals.
More than 200 bodies were recovered from the scene, but it is unclear how many are from those on board the plane, and how many are casualties from the ground.
Details are still emerging from the scene.
Air India flight AI171 left Ahmedabad's Sardar Vallabhbhai Patel International Airport at 13:39 local time (08:09 GMT), Air India said.
It was scheduled to land at London Gatwick at 18:25 BST.
The plane crashed on departure from Ahmedabad - where all operations have since been suspended.
According to flight tracking website FlightRadar24, the signal from the aircraft was lost "less than a minute after take-off".
Flight tracking data ends with the plane at an altitude of 625ft (190m).
The plane gave a mayday call to air traffic control, India's aviation regulator said. No response was given by the aircraft after that.
It crashed into a residential area called Meghani Nagar.
The plane crashed into a building used as doctors' accommodation at the Byramjee Jeejeebhoy Medical College and Civil Hospital.
A photograph taken after the crash shows abandoned tables and plates of food in the canteen of the hostel. At the far end of the room, people have gathered to inspect a huge hole in the wall apparently caused by the impact of the plane.
One woman at the scene told ANI that her son jumped from the second floor of the hostel, sustaining injuries, when the plane crashed there.
Verified footage taken in central Ahmedabad showed huge plumes of black smoke in the sky.
The BBC's Roxy Gagdekar said people near the scene were running to "save as many lives as possible".
He said emergency services were involved in a rescue operation and trying to extinguish a fire, and described seeing bodies being taken from the area.
Indian foreign ministry spokesperson Randhir Jaiswal told a press briefing that "we have lost a lot of people".
Air India later issued a statement confirming 241 people on board the plane had been killed. The airline said the "sole survivor" was being treated in hospital.
Ahmedabad's police chief GS Malik said it was highly likely that there were also casualties on the ground where the plane crashed, and warned that "some locals" would have died.
Air India confirmed that there were 242 passengers and crew members on board the Boeing 787-8 Dreamliner, which has a total of 256 seats.
There were 169 Indians, 53 Britons, seven Portuguese nationals, one Canadian and 12 crew on the plane.
The sole survivor of the crash has been named as Vishwashkumar Ramesh, a British man who was sitting in seat 11A.
He was quoted by Indian media as saying: "Thirty seconds after take-off, there was a loud noise and then the plane crashed. It all happened so quickly."
The BBC spoke to one of his relatives, Ajay Valgi in Leicester, who said Vishwashkumar had called the family to say he was "fine".
Mr Valgi said Vishwashkumar did not know the whereabouts of his brother, also called Ajay, who was also on the plane.
Three Britons from Gloucester - Akeel Nanabawa, his wife Hannaa Vorajee and their daughter Sara - are thought to be among those who were on the flight. In a statement, Gloucester Muslim Society said it was "profoundly heartbroken" and offered its "deepest condolences" to the family.
Ammaarah Taju, the granddaughter of a couple on the plane, told the BBC from her parents' home in Blackburn how the family is "clinging onto hope" they are still alive.
Adam Taju, 72 and his 70-year-old wife Hasina were flying with their son-in-law Altafhusen Patel, 51, who lives in London with his wife.
Leicester East MP Shivani Raja told BBC News she understood there were a "handful of Leicester residents" on board but stressed she was still waiting for "official reports" to confirm the news.
She said her community, which has a high population of British-Gujaratis, were "all really horrified and devastated" by the crash.
An "emergency centre has been activated" and a support team put in place for families seeking information, Air India's chairman Natarajan Chandrasekaran said.
Gatwick Airport said a reception centre for relatives of passengers was being set up and said British nationals with concerns about friends or family should call 0207 008 5000.
The aircraft involved was a Boeing 787-8 Dreamliner, and the Air India crash is the first time it has come down like this.
The model was launched 14 years ago. Just six weeks ago, Boeing lauded the fact that it had reached the milestone of carrying one billion passengers.
Air India operates a fleet of more than 190 planes including 58 Boeing aircraft, according to its website.
In a statement, Boeing said: "We are in contact with Air India regarding Flight 171 and stand ready to support them. Our thoughts are with the passengers, crew, first responders and all affected."
Aviation experts have told the BBC the position of the plane's wing flaps as it took off may have caused a problem for the plane.
One video verified by the BBC shows the plane descending before a large explosion occurs as it hits the ground.
"When I'm looking at this," aviation analyst Geoffrey Thomas said, "the undercarriage is still down but the flaps have been retracted."
Another expert, Terry Tozer, said: "It's very hard to say from the video for sure, it doesn't look as if the flaps are extended and that would be a perfectly obvious explanation for an aircraft not completing its take-off correctly."
"That would point to potential human error if flaps aren't set correctly," said Marco Chan, a former pilot and a senior lecturer at Buckinghamshire New University, "but the resolution of the video is too low to confirm that."