Most of the fatalities occurred in North Carolina, where officials confirmed eight victims.
"Amazing. They did awesome", said Knox, who was stranded with seven others, including a boy who was carried out in a life vest.
A 61-year-old woman died Friday night when her auto struck a tree that fell during the storm, state emergency officials said.
As of Saturday morning, the National Hurricane Center announced that Florence is now a tropical storm with maximum wind speeds of 45 miles per hour and said heavy rains and catastrophic flooding will continue across portions of North and SC.
The tree was about 6 feet above the road surface.
Across the Carolinas, officials are sounding the alarm: More communities will flood as rivers collect water from upstream and spill over.
The Governor urged residents and travellers to avoid driving throughout the state because most roads are still at risk of major flooding as rain continues to hammer down. The great danger now, experts say, is river flooding.
Two others died in the state from carbon monoxide poisoning caused by a generator inside their home, according to a local coroner.
He earlier said the storm system 'is unloading epic amounts of rainfall: in some places, measured in feet, not inches'. By Saturday morning, it had already dumped more than 30 inches (76 cm) of rain, a record for North Carolina.
Colleen Roberts, city public information officer for the area, told BBC World News more than 4,000 homes had been "destroyed or completely damaged" there, based on calls they had received for emergency services.
"The slow motion of the storm will make this a very prolonged flood event", Reid Hawkins, science officer for the National Weather Service office in Wilmington, said in a briefing. A woman in Hampstead, North Carolina died of a heart attack after first responders were unable to reach her fast enough due to downed trees.
The White House said President Trump will tour areas affected by Florence next week, once it is determined that his visit will not disrupt rescue and recovery operations.
With a plodding pace belying still-unspent fury, Tropical Storm Florence pushed deeper into the Carolinas on Saturday, inundating homes, toppling trees and pushing rivers far beyond their banks as rescuers rushed to keep pace.
As of 2:00 pm (1800 GMT), maximum sustained winds had weakened to near 45 miles (75 kilometers) per hour, but the NHC warned residents of risky storm surges and "catastrophic flooding".
But it continued to warn of "catastrophic" flooding from excessive rainfall. Disaster response efforts are underway.
Wind speeds are kicking up far from the coast in central SC as Hurricane Florence slowly makes its way along the coast.
Mike Pollack searches for a drain in the yard of his flooded waterfront home a day after Hurricane Florence hit the area, on September 15, 2018 in Wilmington, North Carolina.
Emergency management officials and nonprofit groups aren't waiting for Florence's rains to end or floodwaters to recede before starting to help people recover from the storm.
The huge levels of rainfall are a result of the storm surge created by the risky tropical weather, which has claimed the lives of 11 people. They wanted a drink'. "We all know that".