Russ,
Dont jump to conclusions. If you have just an oil leak of some type, the LOP, (low oil pressure) switch did its job. Stopped the set before it damaged the engine. Take a good deep breath, then investigate. Engine failure is rare for this gen set.
A quick way to check if the engine is locked up is to open the left side engine door. Squat down and turn your head 45 degrees to the right. You should be looking at the rear bulkhead. There should be a switch there. S10, the so called "Dead Crank Switch." It has three positions. Off, normal and crank. It has many uses. Place the switch in the crank position. The engine should turn over, but NOT start. If she turns over, it's a good sign. Keep your fingers crossed