Stone County Sheriff Doug Rader provided the new fatalities figure and also confirmed that seven people were injured in the accident, one of them seriously, Efe reported.
Some of those who died were children, Rader said, without providing further details.
The boat, a replica of a World War II-era DUK-W amphibious craft, capsized at 7.10 pm Thursday when, according to weather reports, the area was being hit by sustained winds of more than 65 km per hour and gusts of up to 100 kph.
Fourteen of the 31 passengers survived the accident.
Eyewitness video footage widely distributed by United States media outlets on Friday shows the boat being battered by strong waves just a few minutes before it capsized.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
