I have a transmission problem

Our 2001 Mitsubishi Galant lost forward power suddenly while we were driving in heavy rain. The engine starts and idles but the car has no forward power. Is it an electrical problem caused by rain or standing water on the road? We had to be towed. We were driving in heavy rain and suddenly lost transmission power. We coasted to the roadside and ended up having to be towed. The car starts and idles fine. However the check engine light is on and there is no driving power whatsoever. The engine revs but never gets into gear, so to speak. Do we have an electrical issue? Did the heavy rain or standing water on the road cause this? All lights and fans and other auxiliary items seem to work.