Had a very unpleasant experience yesterday. My RS4 suddenly dropped all the oil

Don't know what happened - drove very slowly in low revs and it suddenly sounded a bit strange. 2 min later the oil pressure warning turned on and I switched off the engine at once. And there was oil all over the tarmac... It came from the right side of the engine. Could see that from below - nothing to see from top of the engine.
Has anyone experienced anything like it? And what caused it? My RS4 just passed 100K KM, has been treated like a baby and been serviced even better.
It will be dropped off at Audi tomorrow morning for inspection.
Thanks
Mikael