my truck leaking oil from the bottom and oil pressure is low wwith white smoke on 2003 Dodge Ram 2500

yesterday i bought a 2003 dodge ram 2500 and i was driving it home and the oil pressure guage went low and the truck made a knocking sound and blew alot of white smoke out of the tail pipe and died when i got out i noticed oil all over the road and bottom of truck on frame and supports does anybody know what could of caused this problem

Asked by for the 2003 Dodge Ram 2500