This was an open cage--that is, the screening, wooden, outer shell had been removed, showing the big beast of the jungle, with its keeper in circus costume, seated in the center of the cage on a low stool.
Against the door of this cage the bounding wagon had struck heavily--so heavily that the lock was torn away or broken, and the cage door pulled open.

The roar that went up was a roar of alarm and fright.

And it increased in intensity when the striped beast, with nervously flicking tail, leaped past its keeper and into the street, where it crouched, not knowing what to do with its newly found freedom.
The street was in the wildest tumult.

The horses drawing the cage had been brought to a stop by the driver.

But another horse, frightened by the din and the runaway, broke loose just at that time, and came tearing along, with flaming eyes and distended nostrils, like a Malay running amuck.
Frank sprang toward the head of this horse, for the peril to the stampeding people seemed great.