The child's injured father was hospitalized.
Rescue helicopters and trucks that can navigate floodwaters are also standing by.
The 400-mile wide storm is expected to start slamming the N.C. coast sometime Thursday night or early Friday, then weaken to a tropical storm as it drifts into SC, said John Quagliariello, meteorologist with the National Weather Service in Columbia. Because when flowing river waters meet the ocean surge, there's really nowhere else for the water to go.
"This rainfall will produce catastrophic flash flooding and prolonged significant river flooding", the NHC said.
Florence is about 60 miles (95 km) east-southeast of Wilmington, North Carolina with maximum sustained winds of 90 mph (150 kph), the Miami-based weather forecaster said. The forward speed of Florence has dropped from 17 miles per hour on Wednesday to 10 miles per hour during Thursday afternoon. From a large gray conference room in the center, they have monitored the path of the storm, coordinated with local partners to open shelters and evacuate residents, mobilized first responders, hoped for the best and prepared for the worst. "Just because the wind speeds came down and the intensity of this storm came down to a Category 2, please do not let your guard down", Brock Long, the Federal Emergency Management Agency administrator, told reporters Thursday in Washington.
North Carolina Gov. Roy Cooper urged people to take the storm seriously.
Cooper also points the worst of the storm is yet to come. "Surviving this storm will be a test of endurance, teamwork, common sense and patience". Utility companies said millions were expected to lose power and restoring it could take weeks. Some areas could receive as much as 40 inches (one meter) of rain, forecasters said.
More than 722,000 homes and businesses were without power in North and SC early on Friday, utility officials said.
The impact of Florence will be widespread, with destructive winds, life-threatening storm surge, risky surf, torrential rainfall, flooding and the potential for tornadoes.
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About 10 million people could be affected by the storm and more than 1 million were ordered to evacuate the coasts of the Carolinas and Virginia. The homes of about 10 million were under watches or warnings for the hurricane or tropical storm conditions.
The storm's centre was about 50 miles south of Morehead City at around 11 pm (03:00 GMT Friday).
Coastal towns in the Carolinas were largely empty, and schools and businesses closed as far south as Georgia.
Millions of people are in the path of the Category 1 storm which on Thursday evening was moving west at only 6 miles per hour (9 km/h).
He said hurricane-force winds extended outward 80 miles from the center of the storm and tropical storm-force winds extended almost 200 miles out.
The National Hurricane Center said Florence will eventually break up over the southern Appalachians and make a right hook to the northeast, its rainy remnants moving into the mid-Atlantic states and New England by the middle of next week.
Hurricane Florence brought a storm surge of some 3 meters (10 feet) as it began battering the USA east coast early on Friday.
The hurricane was seen as a major test for the Federal Emergency Management Agency, which was heavily criticized as sluggish and unprepared for Hurricane Maria in Puerto Rico previous year.
Emergency officials on Wrightsville Beach were able to assess the beginning impacts of Hurricane Florence before day turned to night Thursday.
