Four individuals were fishing on lake. As the waves grew larger they headed back. While en-route to shore they had engine problems. Waves began going over rear of boat. Bilge pump was not working. Attempted to start kicker motor but it died. When boat went underwater occupants jumped from boat and attempted to swim to shore. A resort pontoon boat observed this and attempted to rescue boaters.  Two successfully rescued, two disappeared below surface. Waves were 4-5 feet at time of incident. PFD's were in boat but not used.
Blackduck                     