Trying to Prevent a Dryer-Vent Fire?

Please help. My little brother did a junk-ton of laundry and didn't clean the vent.. When I went to clean it, the lint rolled up as i pulled it out and slipped back down the vent.. I tried using a shop-vac to get it out, but that didn't work.. and I have a load of laundry that needs drying... what do I do?