The movies/books that are about AI tend to all forget one thing. Worst case scenario, you can just pull the power plug.
Artificial Intelligence doesn't really imply autonomy unless we choose to add that.
Also AI isn't really the AI people are picturing in their heads when they hear the term. It's just a bunch of clever algorithms that have been "trained" (have accessed) modeling data. There's no real intelligence, it's just clever programming.
There are generally considered to be three stages of AI and we're barely in the 2nd stage - if that. It's impressive and fun, but none of these stages imply autonomy.
I'd say your fear isn't justified, but it's your fear so you should probably decide that for yourself.