Are you stopped or are you driving down the road? Not all cars are identical in what they will do but you have a chance of the steering wheel locking if you turn the key completely off. If you simply turn the key to the accessory position which will cut the power to the motor you will still have steering control but it will be difficult. If you are sitting still when you do this nothing will happen simply place the car in park.
In brief, you will blow the engine.
You run out of your car and check if the person's dead. If he isn't, drive your car away as fast as you can. If he is dead, drive your car away even faster.
If you drive a manual car your shifting isn't correct
Because it can roll away if it is on an incline if left in drive without setting the parking brake. In fact on some vehicles you cannot remove the key with the car in drive. It is a safety feature.
depends on the car
Well you should use the emergancy break or jump out of the car when you have the best chance.
Your car doesn't turn on.
You will lose your power steering and tho you still have brakes your ABS may not function
If its a front wheel drive car , you automatically push the accelerator but not to hard and turn into it not with it. A 4 wheel drive car you turn into it and press the accelerator and finally rear wheel drive you let go of the accelerator and turn into it
You get arrested
You will be ticketed.
You'll damage (probably seriously) the engine and related components such as the transmission and drive-shaft - how bad will depend on how "off" the timing is.