some development nearby? When people clearing land for project they/we actually invading the animal homes. No home to go destroy by human so invading your home till you found them and kill them or they die of starvation no food to eat.

One other possibility is someone rear snake as hobby and then decided to let them go to the bushes near your home thinking it will survive in the "wild" but the domesticated snakes find it hard everywhere it goes and ended up at your home. Then of course the human race we always kill as long as it present some threat.