Police have identified the victims as 43-year-old Juan Torres of Huntington Station, and a married couple, 45-year-old Patrick Franklin of Port Jefferson and his wife, 44-year-old Susan Franklin.
Investigators say a friend of the victims rode out to the house boat after he hadn't heard from them in a while.
Once he made it on board the 38-foot long house boat, he made the tragic discovery.
All three of his friends, Mr. and Mrs. Franklin and Juan Torres, were found unconscious shortly after 9 p.m. on West Shore Road near Margo Lane in Huntington Harbor.
He immediately called 911, and soon after, first responders were on board the house boat trying to save their lives.
"They were transported to shore. Then the three were transported to Huntington Hospital, where they were pronounced dead in the emergency room," Detective Sgt. Thomas Groneman said.
Investigators say there is no sign of foul play. They believe a generator may be involved.
"We will do a forensic analysis and an inspection on the boat to see what actually caused the deaths," Groneman said.
The friend who discovered the three victims and two officers had to be treated at the hospital because of the fumes.