A sheriff's deputy and a corrections officer were both killed in a two-car crash in Florida's Hardee County and another person died in a vehicle accident near Orlando that was deemed storm-related.
Florida Power & Light, the nation's third-largest electric utility, warned Friday it was expecting "unprecedented" power outages, and that it could affect about 9 million people.
Further north, Miami Beach residents were permitted to return, too.
The warnings pertained mostly to communities along the St. Johns River, where storm surges were expected to push water four to six feet above normal high-tide levels.
Irma killed 43 people in the Caribbean and at least 11 in Florida, Georgia and SC. Over 350 people were rescued from the flooding, but no casualties were reported there. There is also the threat of brief tornadoes that could spread from south to north sometime Monday. Naples saw almost 12 inches of rain and a 7-foot storm surge.
Scott cautioned that the deadly storm, which weakened slightly Saturday morning to a Category 3 with 125-mph winds, would cause "life-threatening" surges as high as 12 feet. This included flood-prone areas in Miami Beach and on the mainland, according to NBC Miami.
"The windows started cracking, and these are massive-impact windows". A deputy and a paramedic, who had just escorted an elderly patient to safety, were trapped for two hours until a crew could free them.
A man died in Worth County, Georgia, on Monday while repairing the roof of a shed during heavy winds, a National Weather Service report said.
Half of the Keys' economy depends directly on tourism - a $2.7 billion industry - according to county officials.
"There are so many areas that you would never have thought would have flooded that have flooded", Florida Governor Rick Scott told reporters after a helicopter tour of the area.
"I'm lifting the evacuation order, effective three minutes ago, 8 a.m., so to the people of Jacksonville that evacuated, please feel free to come back home", Curry said. Fumes from a portable gas generator appeared to have been running inside the house, and the individuals were overcome by fumes.
"Sometimes people listen and sometimes they don't", Long said. The outages range from the coast to far inland cities such as Charlotte and Asheville in North Carolina and Greenville in SC.
French President Emmanuel Macron is set to head to hurricane-battered Caribbean island of St Martin on Tuesday.