Gov. Nathan Deal declared a state of emergency for much of coastal Georgia on Tuesday as Hurricane Matthew menaced the nation's east coast, forcing state officials to ready evacuation plans and sending residents along the shore scurrying for supplies.

Forecasters predicted the Category 4 storm, which pounded Haiti with 145-mile-per-hour winds after making landfall early Tuesday, could slam into Florida's Atlantic coast by Thursday and then rake Georgia, South Carolina and North Carolina.

Deal said he was prepared to order residents in Savannah and other low-lying coastal areas to evacuate if needed, though he said the massive storm was still too far away to predict its definite path. Georgia has not had a direct hit from a hurricane in more than a century.

“We are prepared to order an evacuation. We are hopeful that’s not going to be necessary in that case," said Deal. "We have been very lucky so far.”

Asked what might trigger an evacuation order, Deal said: "That's left up to Matthew."

Residents up and down the East Coast were preparing for the storm, with thousands flocking to stock up on groceries and gas as Matthew churned ahead. South Carolina Gov. Nikki Haley outlined plans to evacuate more than 1 million people on the coast.

Deal said he's ordered the Georgia Emergency Management Agency to work with state and local agencies to prepare for the storm. A state emergency response center opened Monday and staff and resources are being shifted to the coast. Federal emergency agencies have also sent staff to Georgia.

Authorities along the Georgia coast ratcheted up their preparations for Matthew, taking a better safe than sorry approach. Tybee Island Mayor Jason Buelterman urged residents to prepare for the worst and instructed city workers to board up public buildings.

“Tybee Island is inside the cone of uncertainty, so procedures dictate we proceed as if planning for a direct hit,” read an alert issued by the coastal community.

Georgia’s barrier islands would likely be the first to evacuate if the storm is tracking to slam into Georgia’s coast, and officials are just as worried about the storm surge from inches and inches of rain – forecasters warned as much as 40 inches fell in some areas of Hispaniola – as they are about the winds.

"The safety of Georgians is our first priority, and we urge residents in these areas to remain calm but vigilant as they prepare for potential impact," Deal said.

Jim Butterworth, the emergency agency's chief, said state officials are ready to reverse lanes on I-16 if an evacuation is necessary. State officials are mindful of what happened in South Carolina in 1999, when emergency officials didn’t reverse the lanes on Interstate 26 and a two-hour trip from Charleston to Columbia took some drivers an entire day.

The governor and Butterworth also urged residents in coastal areas to stock up and keep close track of the storm's path, which can defy forecaster predictions.

"Be prepared individually, because that preparation is critical," said Butterworth.

The state of emergency, which extends to Oct. 12, includes Brantley, Bryan, Bulloch, Camden, Charlton, Chatham, Effingham, Evans, Glynn, Liberty, Long, McIntosh and Wayne counties.

The Associated Press contributed to this report.