My oven stopped working midway baking. Top burners and broiler works, internal temp won't go above 140, help?

We have a 15 year Kenmore gas oven which has been totally reliable until now. I have half baked brownies now, any ideas on what is wrong with our oven? We've tried turning off the oven and resetting a few times, but nothing helps. Broiler is very hot though, do they work on the same pilot?