At least two women from United Kingdom were killed and 20 injured as special toy train derails on Kalka-Shimla railway track in Haryana on Saturday, 12 September, according to reports.

Three out of four coaches of the special chartered train went off the tracks after an hour into journey at around 12:40pm on Saturday, between Taksal and Kalka stations in Haryana, said TV reports.

There were 37 passengers in the toy train, ANI reported. The injured have been admitted to Parwanoo ESI Hospital in Solan District, Himachal Pradesh.

"The reason behind the incident is yet to ascertained. It might be a problem in the track or in the coach. There is a possibility that an animal suddenly came on the track or rocks falling on track leading to the derailment," IANS quoted Northern Railway CPRO Neeraj Sharma as saying.

The toy train line from Kalka to Shimla was opened to public on 9 November 1903 and has been a major tourist attraction ever since, especially for foreigners.  It has been listed as one of the UNESCO world heritage site in 2008.

Check out first visuals and latest updates on toy train derailment: