UPDATE FRIDAY 11:15 A.M:
Fire inspectors with the Cape Coral Fire Department and the State Fire Marshals Office have concluded that the cause of the fire is undetermined; however, they are unable to rule out electrical.
Firefighters will remain on scene throughout the day to extinguish any hot spots that could arise.
UPDATE FRIDAY 7:40 A.M.:
Cape Coral Fire says three employees tried to put out the fire with an extinguisher before the blaze spread.
According to the Batallion Chief Ian Milliken, different coolers, alcohol and strong winds made the fire harder to put out. Milliken says there was only one fire hydrant nearby, so water supply became an issue.
FOX 4 Because of the large blaze, the fire department brought in a fire boat to attack the flames from the river. Crews used water from the Caloosahatchee River to help put it out.
PHOTOS: Boathouse Tiki Bar and Grill fire in south Cape Coral
They were able to contain it, but stayed on scene Friday morning to watch it for hot spots and flare-ups.