Seven Britons were among 19 people killed when a small plane crashed shortly after take-off from the Nepalese capital of Kathmandu.
Police say everyone on board the twin-engine propeller-driven Dornier aircraft died in the accident, also including five Chinese and seven Nepalese.
Tour operator Sherpa Adventures confirmed the deaths.
Owned by private firm Sita Air, the plane had taken off for Lukla in the Mount Everest region when it plunged into the banks of the Manohara River near Tribhuvan Airport.
The pilot reported trouble two minutes after take-off in clear weather and Kathmandu airport official Ratish Chandra Suman said the plane had hit a bird.
"Immediately after the take off, the air traffic controllers noticed the aircraft making unusual manoeuvres," he said.
"When the controller asked the pilot about it, he said the plane had struck a bird."
Nepal Police spokesman Binod Singh said: "The pilots seem to have tried to land it safely on the banks of the river but unfortunately the plane caught fire."
Nepal police officer Rajan Adhikari said: "The plane was engulfed in flames when we arrived."
Local television channels showed dozens of soldiers and police officers picking through the smouldering wreckage of the aircraft with a large crowd of shocked bystanders watching.
A number of badly-burned bodies were laid in a line a few metres from the plane's shattered fuselage.
A witness told Kantipur Television: "I was just walking and saw a plane landing. It was on fire and I even heard people inside the plane screaming."
It is the sixth fatal crash in Nepal in less than two years. Aircraft and pilots often have to contend with bad weather and difficult landing strips in the Himalayan nation.
The British Foreign Office said it was "urgently" seeking to confirm the number of dead and their identities.
"The embassy in Kathmandu is in contact with the Nepalese authorities and the British ambassador has already been to the hospital where we understand the bodies were taken," a spokeswoman said.
The Foreign Office has set up a helpline for concerned relatives on 0207 008 1500.
Thousands of Westerners head to the Himalayas every year to trek in the region around Mt Everest, the world's highest peak. Autumn is the peak climbing season in Nepal.
The country has a poor road network and large numbers of tourists, pilgrims and climbers rely on Nepal's 16 domestic airlines and 49 airports to reach remote areas.