Trans oil lost on 2000 Hyundai Elantra

Lost trans/oil smoked with no warning. Why so.

Asked by for the 2000 Hyundai Elantra
maybe due for a tranny inspection and flush. lost fluid means possible seal issue. take it to the shop.
Thanks was towed and serviced. Back on the road....minor issue. Pretty cheap fix. Great mechanic in Bronx. Thanks again.
good show. good mechanics are good find.