My transmission stopped engaging at a stoplight

03 Toyota Matrix slight trans leakage until I stopped at a light and was barely able to limp drive it off the road. Towed home , found and fixed a loose hose from the top, added 1gal trans fluid, started vehicle, hose repair fine, put into gear and easily a quart gushed out in a thick stream before engine off and back into park. The pan is dry all the way around, and a small drip continued from up higher and in between trans pan and oil pan. My question is of course, what the hey is located in that area that can release that much fluid at once? Thank you for any advice on this matter.