Indeed, it was all so simple that Fix and Passepartout felt their hearts beating as if they would crack.
They were listening for the whistle agreed upon, when suddenly savage cries resounded in the air, accompanied by reports which certainly did not issue from the car where the duellists were.

The reports continued in front and the whole length of the train.

Cries of terror proceeded from the interior of the cars.
Colonel Proctor and Mr.Fogg, revolvers in hand, hastily quitted their prison, and rushed forward where the noise was most clamorous.

They then perceived that the train was attacked by a band of Sioux.
This was not the first attempt of these daring Indians, for more than once they had waylaid trains on the road.

A hundred of them had, according to their habit, jumped upon the steps without stopping the train, with the ease of a clown mounting a horse at full gallop.
The Sioux were armed with guns, from which came the reports, to which the passengers, who were almost all armed, responded by revolver-shots.
The Indians had first mounted the engine, and half stunned the engineer and stoker with blows from their muskets.