Tap the gas pedal to try to unstick the throttle linkage.
Hook your toe under the pedal to try and free it.
Shift to neutral and apply firm pressure to the brakes without locking the wheels.
Find a safe place to move the vehicle completely off the road.
If your automobile has power steering or a locking steering wheel, do not turn off the ignition or you will lose either your power steering, or the ability to steer.
Have your vehicle checked with a mechanic as soon as possible.