This would usually happen because of skeletons. If the skeleton shoots a creeper when the creeper isn't targeting a player, It would most likely explode. Because of this, creepers would explode holes in a wall that surrounds a village and puts the village in danger. Raiders got through the wall hole which was caused by creeper exploding after accidentally being shot by a skeleton trying to shoot an iron golem. What I mean by "isn't targeting the player" is that the creeper doesn't detect the player.