More than 2.6 million homes and businesses from Louisiana to Virginia were left without power at the peak of outages.
Zeta weakened to a Category 1 storm over the course of the first day after it made landfall as a hurricane and moved into Southern Mississippi, but forecasters continued to warn about the dangers of the storm.
Gov. John Bel Edwards called the damage in Louisiana “catastrophic” and ordered the Louisiana National Guard to fly in soldiers to assist with search-and-rescue efforts.
Residents across the South have already dealt with repeated onslaughts from hurricanes over the last few months, but Zeta was not expected to be as strong or cause such damage.
The storm ripped off rooftops and pulled down trees everywhere. Mayor Sheldon Day of Thomasville, Ala., said hundreds of trees fell in roads and on homes, while some gas station canopies blew over.
“At one point, every major thoroughfare was blocked by trees,” Day said.
Six people have died due to hazardous conditions during and after the hurricane.
A man was electrocuted in New Orleans, and four people died in Alabama and Georgia when trees fell on homes, authorities said, including two people who were pinned to their bed. In Biloxi, Mississippi, a man drowned when he was trapped in rising seawater.
The very system that was meant to break Zeta up instead fed into it, causing the system to rapidly gain strength and become a category 3 hurricane when it made landfall in Louisiana.
States across the region felt the hit, with snap snowstorms in Oklahoma while winds lashed the Carolinas. In South Carolina, hundreds of trees came down, pulling down powerlines and crashing in rooftops where they fell, Weather.com reported.
"We had lots of wind damage with trees down. There's been trees down with a lot of damage to homes. Highway 14 was blocked by a downed tree and power line. We are busy getting the trees cleared," Landrum Mayor Robert Briggs said.
Atlanta instituted a tropical storm warning for the second time ever, with the storm leaving over 1 million homes and businesses without power.
Georgia Power said its website and mobile app were overwhelmed with high volumes of traffic.
The Associated Press contributed to this report.