1998 Nissan Altima Huge, sudden oil leak

Hello,

I have a 98 Nissan Altima with around 135,000 miles on it. The car ran perfectly fine one day, then developed a major oil leak the next. The oil seemed to be leaking onto the serpentine belt on the side of the engine. The belts then sprayed the oil everywhere else. It would leak out four quarts in a matter of minutes. This is a big problem because this is the only vehicle I had to rely on. I have read that it may be a gasket or seal of some sort but I am not too sure. I was wondering if you could determine what the problem may be and how I would go about repairing the situation.