A shopper looks for items on nearly empty Walmart shelves in Boynton Beach ahead of the arrival of Hurricane Dorian. (AFP)

Hurricane Dorian strengthened into a major storm packing winds of 115 miles per hour (185 kilometers per hour) on Friday as it bore down on the Bahamas and the east coast of the US state of Florida.

Bahamas Prime Minister Hubert Minnis warned residents of the Atlantic Ocean archipelago in the path of the “very powerful and potentially life-threatening hurricane” to evacuate.

The Miami-based National Hurricane Center (NHC) said Dorian, which is expected to make landfall in the Bahamas on Sunday and in Florida late Monday or Tuesday, had gone from a Category 2 to a Category 3 storm on the five-level scale.

At 5:00 pm (2100 GMT), Dorian was 420 miles (675 kilometers) east of the northwestern Bahamas and 595 miles east of West Palm Beach, Florida, and moving in a west-northwest direction at nine miles per hour, the NHC said.

Dorian is an “extremely dangerous hurricane” and could be a Category 4 storm when it makes landfall in Florida.

The northwestern Bahamas should prepare for life-threatening storm surge that could raise water levels by as much as 10 to 15 feet (three to 4.5 meters) above normal tide levels, the NHC said.

The surge will be accompanied by large and destructive waves,” it said, and heavy rainfall could cause flash floods.

“Those who refuse to evacuate place themselves in very great danger,” Minnis, the Bahamas prime minister, told a press conference. “Do not put your life and those of your loved ones at unnecessary risk.

“Do not be foolish and try to brave out this hurricane,” Minnis said. “The price you may pay for not evacuating is your life.”

With the path of the storm still uncertain, coastal Florida residents were not under evacuation orders yet but were stocking up on food, water and other supplies and making preparations to flee their homes.

Florida Governor Ron DeSantis issued a declaration of emergency for all of the state’s 67 counties and urged its millions of residents to make preparations for what he said could be a “major event.”

“We’re anticipating a massive amount of flooding,” DeSantis said. “We urge all Floridians to have seven days’ worth of food, medicine, and water.”

“If you’re in an evacuation zone and you’re ordered to evacuate, please do so,” DeSantis said.

The Florida National Guard said about 2,000 service members had been mobilized so far and another 2,000 would be on Saturday.

President Donald Trump, whose Mar-a-Lago golf club is located in Palm Beach, said that Dorian was “looking like it could be an absolute monster” and canceled a trip to Poland to stay behind and focus on preparations for the storm.

“All indications are it’s going to hit very hard,” Trump said in a video.

“Some people said bigger or at least as big as Andrew,” a Category 5 storm that left 65 people dead in 1992, he said.

Trump declared a state of emergency in Florida authorizing federal assistance to supplement state and local efforts.

Georgia — another southeastern state that could be in the storm’s path — has declared a state of emergency for 12 counties.

Governor Brian Kemp said the hurricane “has the potential to produce catastrophic impacts to citizens” throughout the southeast coastal region of the United States.

The US Coast Guard said ocean-going commercial vessels should make plans to leave south Florida ports.

A number of schools announced that classes would be canceled until at least Tuesday.

Orlando International Airport said it would halt commercial flights at 2 am (0600 GMT) on Monday “out of an abundance of caution.” Orlando is the main airport for nearby Disney World.

NASA is also close by and the US space agency said it was moving an enormous mobile rocket launcher from a launch pad into a vehicle assembly building to protect it from the storm.

A Rolling Stones concert in Miami originally scheduled for Saturday night was moved up by a day due to the weather forecast, the band said on its Twitter account.