Transmission Fluid Leaking problems of the 2011 Kia Motor Forte

The check engine light came on, I heard a sound like metal scraping metal, I was driving about 20mph going straight down s. Main st downtown warrenton, oregon and was planning to pull over when suddenly my car stopped dead after a horrible noise of what sounded like a heavy metal snapping/crunching noise. I looked under the hood and everything looked ok, but some black fluid was dripping onto the ground. The oil had been changed about four days before this and they said it was 2. 5 quarts low. I had also taken it to an auto repair shop to see if it needed any immediate attention as it was making an odd scraping noise before the oil was changed and he said he suggested some thing to do with the cam but it wasn't urgent and to just keep the oil filled in case there is a leak somewhere. The oil reservoir was full when I left that morning when it seized up. If I had been going much faster, I would probably have been killed as it stopped completely, no coasting to a stop. It just stopped. From 20mph to 0 and the car jumped when it stopped. I did not touch the brakes. It was towed to mark's auto repair in seaside, oregon. He has no idea what caused the problem but did say that metal flakes are in the oil and transmission fluid and other places too. He has a work order he is working up but said he would need to replace the engine at a minimum. They can only find short blocks for sale at this time and so the estimate is based on using a short block. My oil gets changed regularly either at kia or a local oil change shop.