I just learned something new (thanks youtube suggestions)
Runaway diesel engine, a scary thing. Apparently an oil leak from bad rings or turbo seal or head gasket can fuel the engine (running on the oil) at full throttle until the source of oil runs out. Turning the ignition off won't stop it, cutting the fuel line won't stop it. The engine needs to either be stalled, which is hard due to the full throttle power output, or suffocated Ideally with a non flammable gas.
It's good to know it can happen, and how to stop it, but it's dangerous as you don't know if the engine will just explode from such stress.