The effects of Tropical Storm Helene are being felt in South Carolina as waves crash over the seawall and onto nearby buildings in downtown Charleston. A tropical storm warning is in effect for the city and the surrounding coast.

Various hurricane and tropical storm warnings across Florida have been lifted or downgraded as Helene moves far north through Georgia, National Hurricane said in its 5 a.m. ET update reclassifying Helene as a tropical storm.

• Hurricane and tropical storm warnings have been discontinued along Florida's east coast south of the Flagler-Volusia county line, the National Hurricane Center said in a 5 a.m. update.
• A hurricane warning along Florida's north coast, from the mouth of the Suwannee River to Mexico Beach, has been downgraded to a tropical storm warning.
• A tropical storm warning has ended for Florida's Gulf Coast west of Indian Pass.
• A storm surge warning for the Florida coast west of Indian Pass and south of Bonita Beach has also been terminated.
• However, a storm surge warning remains in effect for Indian Pass to Bonita Beach and Tampa Bay.

The extent of the damage caused by Hurricane Helene will not be felt until sunrise, but the affected region's power grid is already in shambles and two million people are left in the dark.

According to PowerOutage.us, 1.2 million people are without power in Florida, 683,000 in Georgia and 242,000 in South Carolina.

Helene arrived last night as a Category 4 storm, the second strongest possible rating on the Saffir-Simpson scale. The National Hurricane Center's hurricane strength guide says energy infrastructure could be damaged for weeks or even months in the event of such a storm.

People in Georgia should continue to shelter from Hurricane Helene and stay away from windows in what the National Hurricane Center called a “dangerous and life-threatening situation” this morning.

The NHC said in an update at 4 a.m. ET that the storm was moving quickly inland across the state, bringing winds of up to 77 mph and heavy rain.

Hurricane Helene has weakened to a Category 1 storm but still poses a major threat to 12 states. NBC News' Jay Gray reports from Tallahassee, Florida, where residents escaped a direct hit.