A man has died after setting himself on fire on board a Japanese Shinkansen bullet train.
Another passenger, a woman in her 50s, was also killed and more than 20 injured, two seriously.
Witnesses said the man, reportedly aged 71, had poured fuel over himself in the first carriage of the train and used a lighter to ignite it.
Most of the 1,000 people on board escaped the smoke-filled carriages when the train made an emergency stop.
The train, a super-fast Nozomi going from Tokyo to Osaka, was near Odawara city south of the capital, when the emergency stop button was pressed.
All trains on the Tokyo-Osaka high speed line were stopped - signs at Odawara station said staff did not know when it would resume operating.
Officials have given no indication of the man's motives but are treating the incident as a suicide.
One unidentified witness said the man had been carrying a petrol container "and sprayed liquid across the seats and then all over himself and then set himself on fire".
"The fire spread all over the place immediately," he told Reuters.
Rupert Wingfield-Hayes, BBC News, Tokyo
This incident will be profoundly shocking to people in Japan. This is an extremely safe country, and Japan's famous bullet train is the safest in the world.
It has not recorded a single fatality since it started operation more than 50 years ago.
Sadly though, Japan is no stranger to suicide, especially among young men. Last year this country again reported the highest rate of suicide in the world, and it is now the leading cause of death for men between the ages of 20 and 44.
There is also a history of people setting themselves on fire in protest. Last year a man died after setting himself on fire in a park in central Tokyo. He was protesting at government plans to overturn Japan's post-war pacifist constitution.
Local media said the incident took place at 11:30am local time (02:30 GMT) while the train was between Yokohama and Odawara.
Japan Rail officials said the train came to a stop after the emergency button was pressed and the man who set himself on fire was then discovered near the toilet stall.
The Kyodo news agency quoted transport officials as saying the driver had tried to put out the fire.
The other dead passenger, a woman, was reportedly found at the other end of the carriage. It was not immediately clear how she had died but officials said it may have been from the effect of the smoke.
Television footage showed people being removed from the train by emergency services and carried across the tracks on stretchers.