I believe Kami the OP pointed out his was overheating. A coolant leak contributes to overheating. I have every reason to believe this was an overheat issue. All these modern vehicles run very hot as it is to meet EPA/AQMD standards.I know there's different levels of mechanical ability with folks but this is about as simple as it gets. Temp gauge fine/no temp dummy light and there's steam=coolant leak. Driving with Temp gauge pegged/Temp dummy light on until steam is visible=overheating.
We can only hope the engine was shut down in time so as to not do damage to it. Even if it went into limp mode the damage may already be done. We are all speculating at this point until it is diagnosed at the dealer.
One thing I do recommend is for Kami, is to make sure everything that can be effected by a overheat issue is checked thoroughly. A drastic overheat issue can be detrimental on a modern direct injected turbo motor.