As Hurricane Dorian threatens, an evacuation order affecting 820,000 people along the entire South Carolina coast went into effect Monday afternoon.

So far, evacuations have gone well, Gov. Henry McMaster said. He pointed out that transportation officials reversed all lanes of Interstate 26 about four hours earlier than planned Monday after noticing traffic jams from evacuees and vacationers heading home on Labor Day.

Officials were encouraging people to leave before tropical storm force winds arrive on Hilton Head Island sometime Wednesday and move up the coast for 24 hours.

WHAT YOU NEED TO KNOW ABOUT DORIAN'S PATH

McMaster ordered coastal schools and government offices closed Tuesday, but said he would wait and see how many schools might be needed for shelters before talking to districts about canceling classes in inland areas later this week.

Georgia Gov. Brian Kemp urged people living along the coast to escape ahead of Hurricane Dorian, citing the storm's powerful winds and uncertain path. He issued an executive order Monday night freeing up 2,000 members of the National Guard to prepare for hurricane response and recovery.

The governor told reporters Monday in Savannah: “This is not one to play with.”

Kemp said people living on Georgia's barrier islands especially ought to get out, warning that emergency responders may not be able to reach them if causeways get flooded or blocked by debris. Georgia officials have planned to turn Interstate 16 linking Savannah and Macon into a one-way evacuation route Tuesday.

In Florida, state officials said more than 70 nursing homes and assisted living facilities along the Atlantic coast, as well as seven hospitals, were evacuated. Disney World announced it would close early Tuesday, and Sea World -- also in Orlando -- announced it would stay closed all day.

CONTINUING COVERAGE OF HURRICANE DORIAN ON FOX NEWS CHANNEL

Warnings also were ramping up along the North Carolina coast as well with Dorian still days away.

Gov. Roy Cooper declared a state of emergency Saturday for the entire state, saying he’s activated 300 members of the National Guard to help with preparations and storm response.

North Carolina officials also said they expect far less rain or flooding from Dorian than the state experienced during Florence last year.

Florence was blamed for 45 storm-related deaths in North Carolina and the National Hurricane Center listed it as causing $22 billion in damage.

A state of emergency also took effect in Virginia.

“Hurricane Dorian is a serious storm, and current predictions indicate that it may affect parts of Virginia,” Gov. Ralph Northam said. “I am declaring a state of emergency to ensure that localities and communities have the appropriate level of assistance, and to coordinate the Commonwealth’s response to any potential impacts from Hurricane Dorian. I encourage Virginians to take all necessary precautions to make sure they are prepared as well.”

Northam took the action Monday anticipating the storm would start to show its effects in southeastern Virginia on Thursday. Dorian could trigger include coastal and inland flooding and prolonged power outages.

The hurricane unleashed massive flooding across the Bahamas on Monday, pummeling the islands with so much wind and water that officials urged people to find floatation devices and grab hammers to break out of their attics if necessary.

The fearsome Category 4 storm slowed almost to a standstill as it shredded roofs, hurled cars and forced even rescue crews to take shelter until the onslaught passed.

Back in the United States, the National Hurricane Center extended watches and warnings across the Florida and Georgia coasts. Forecasters expected Dorian to stay off shore, but meteorologist Daniel Brown cautioned that “only a small deviation” could draw the storm’s dangerous core toward land.

By 10 p.m. ET Monday, the storm’s top sustained winds remained steady at 140 mph. It had been crawling along Grand Bahama Island at 1 mph and then remained stationary.

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Dorian was likely to begin pulling away from the Bahamas early Tuesday and curving to the northeast parallel to the southeastern coast of the U.S.

The system is expected to spin 40 to 50 miles off Florida, with hurricane-force wind speeds extending about 35 miles to the west.

Fox News' Mike Arroyo contributed to this report.