1997 Hyundai Elantra Clutch pedal goes down without resista

When I started driving my car this morning the clutch pedal had resistance and operated fine. Around 15 miles later I lost any feeling of resistance in the clutch pedal. I pushed the pedal down and could not engage any gear or take it out of gear. The fluid in the resevour is full, I don't see any leaking from under the dash where the pedal is.