Captain John Harvey, who often said, "When you least expect Indians, there they are", accompanied by ten men, made a surveying expedition into the wilds of Burnet County during June of 1839, and a Mr. Burnet was on guard during the night. The snorting of one of the pack mules first aroused his suspicion but no Indians could be seen in the darkness. All remained quiet until just before day when Captain Harvey attempted to awake the remaining members of his party. As he did the surveyors were unexpectedly fired upon by Indians concealed in the nearby bushes. The Texans became somewhat disorganized and three of the number ran entirely away. Those who remained soon rallied and in a few moments a fierce fight followed. One warrior anxious to steal a fine horse staked nearby, left his place of concealment and was in the act of cutting the rope when three individuals fired and shot him down. The Indians believed a wounded warrior could not go to the Happy Hunting Grounds if he were scalped by the enemy. That being the case, almost invariably they resorted to extreme measures to recover the bodies of their dead and wounded. So on this occasion, several warriors rushed forward to recover the body of the dead warrior. The Indians then retreated and accidentally ran into two of the white men who had run away. This, of course, only augmented their fright and they became completely lost from their companions. Eight days later, however, after wandering among the wilds, the two lost men reached Austin. The third man successfully found his way back to his companions.
The above story is from the book, The West Texas Frontier, by Joseph Carroll McConnell.
J.W. Wilbarger provides a more detailed description of the encounter in his book Indian Depredations in Texas: