Could it be Water Pump or Head Gasket? on 1993 Volvo 940

I noticed my reserve tank for coolant hasnt been holding coolant--I saw a small what looks like a pipe line leaking from under the car--but the other day my car was smoking after i put the heat on--it was coming from under the hood--all of my coolant then flushed out from under car too--Im wondering what could it be?

Asked by for the 1993 Volvo 940
You need to stop driving this car before you do damage that you can not afford.
You need to take it to a repair shop and find the coolant leak and fix it NOW!