AT the moment the pit is full of water and I am concerned that water will be flooding my basement at any moment. I unplugged the unit since it would not stop. Pushing the switch up or down does not stop the motor and the ball sits below water level and it is not draining.
1. What could be the problem; and
2. What can I do to prevent any flooding until a plumber arrives (it is 5:00am)

You say the float ball's beneath the water, the pumps running and the pumps not putting out? Is the pump running or humming? If that's so it sounds like the intake is clogged. (see image). Shut the pump off and check the inlet screen for a blockage. Good luck, Tom