"A passenger poured oil over himself in the first carriage of the train," a Japan Rail spokesman was quoted as saying.
Japanese local TV media showed still pictures of the train halted with white smoke coming out of it.
According to media reports, the incident took place at 11:30am local time (02:30 GMT) while the train was between Yokohama and Odawara.
The reports also said that two people had suffered cardiac arrests.
Bullet trains, which have a good safety history, travel at speeds of up to 320km/h.