A thundering volley crashed from the rifles of the outlaws, answered by a rattling fire from the revolvers of the Rangers. Tad heard an outlaw utter an exclamation of pain and knew that one at least of the bad men had been raked by a bullet.
"Back!" came the command from the leader of the bandits. The word was not spoken loud enough to be heard far away, but every man there heard it, and back they rushed into the cave. A shower of dirt fell over the two Pony Rider Boys, who were by this time crawling on all fours to get away from the tree that they knew would come down with a bump.
It did. The Rangers were still shooting. Tad and Stacy were in a dangerous position. The Rangers were firing right over them. The instant the boys heard the base of the tree fall into place, Tad uttered the owl call.
"Don't shoot, don't shoot!" howled Chunky.
"It's the boys! Stand fast. Lie low!" commanded the Ranger captain.
"Something is going on here that we don't know about."
A moment later Tad and Chunky came staggering into the arms of their friends.
"Surround the base of the tree. They're in the cave," cried Tad.
"Wait, wait!" commanded the Ranger.
In the cave the outlaws were beginning to think. Tad's shots had been laid to the carelessness of one of the men. Each one denied that he had fired them.
"That was a signal. Somebody here is a traitor!" cried the leader.