Bullet train passengers and attendants were treated for heat stroke yesterday, after the air-conditioning system broke down on a service between Nanchang in Jiangxi Province and Shanghai.

When the train reached Shangrao Railway Station, Jiangxi Province, people rushed out onto the platform to cool themselves down. One little boy stripped naked.

Hundreds of people were left sweltering in enclosed carriages, before being taken off at Jiangshan in Zhejiang Province. Part of the train was unaffected and continued to Shanghai as scheduled.

The 16-carriage train set off from Nanchang around 9am. Witnesses said soon after the train left Nanchang Railway Station the air-conditioning system broke down.

Carriages in the first part of the train were soon extremely hot and uncomfortable.

A Shanghai web user on the train took photographs of the scene. One showed a baby crying and in distress.

"It was just like sauna," said netizen Wang Youlin.

When the train reached Shangrao Railway Station, Jiangxi Province, people rushed out onto the platform to cool themselves down. One little boy stripped naked.

On the way from Shangrao to Jiangshan, some passengers tried to smash the windows to change the air, said a Shanghai passenger named Wang Zhong on his microblog.

The train reached Jiangshan around 12pm. Some passengers and train attendants had suffered heat stroke and were rushed to hospital.

Shanghai railway authorities sent a rescue train to Jiangshan. Passengers finally reached Hongqiao Railway Station at 4pm, two hours after the scheduled arrival.

The Shanghai Railway Bureau did not comment.