WASHINGTON, Sept. 10 (Xinhua) -- Florence, which is approaching the southeastern coast of the United States, has become a Category 4 hurricane, the second-strongest on the Saffir-Simpson scale, the U.S. National Hurricane Center (NHC) said Monday.

The center of Florence was located about 1,950 kilometers east-southeast of Cape Fear, state of North Carolina, packing maximum sustained winds of 195 km per hour (kph), moving west at 20 kph, according to an update published by the weather forecaster.

The NHC said in an earlier advisory that the center of the system will move over the southwestern Atlantic Ocean between Bermuda and the Bahamas Tuesday and Wednesday before approaching the coast of South Caroline or North Caroline on Thursday, bring heavy rain that could cause severe flooding through the region.

North Carolina Governor Roy Cooper told a press conference Monday that the state is in the "bull's eye" of the rapidly intensifying storm.

"This storm is strong and it's getting stronger," said Cooper. The state has issued mandatory evacuations.

According to local reports, officials ordered residents and visitors to begin evacuating the Outer Banks, a 320-kilometer-long string of barrier islands and spits off the coast of North Carolina and southeastern Virginia.

Cooper, who already declared a state of emergency, said he asked President Donald Trump for a federal disaster declaration so that resources will be ready when the storm arrives.

States of South Carolina and Virginia are also preparing for the impact of Florence.

South Carolina emergency management officials said they were "preparing for the possibility of a large-scale disaster." About 750 National Guard members were expected on duty in the state.

About 1 million people have been ordered to flee the South Carolina coast beginning Tuesday.

The U.S. Navy is sending about 30 of its Virginia-based ships out to sea as Florence barrels toward the Atlantic Coast.

A Navy spokeswoman said the ships will disembark Monday from naval bases and will head to portions of the Atlantic to avoid damage.

The United States was hit by a series of catastrophic hurricanes last year, including Hurricane Maria, which killed some 3,000 people in Puerto Rico, and Hurricane Harvey, which killed about 68 people and caused an estimated damage of 1.25 billion U.S. dollars.

A Trump campaign official announced Monday that the president, whose administration faced severe criticism for a slow response in Puerto Rico to Maria, has canceled a rally originally planned for Friday in Jackson, state of Mississippi, because of safety concerns due to the approach of Florence.

Hurricanes reaching Category 3 and higher are considered major hurricanes because of their potential in causing a significant loss of life and damage.

Florence, the first major hurricane of the Atlantic season, was once a Category 4 hurricane last week, packing maximum sustained winds of 215 kph, before weakening gradually to a tropical storm, which regained hurricane strength Sunday morning.

Officials said the largest threat to life from hurricanes is not the high winds, noting that flooding is the deadliest result of these storms.

Florence is one of three hurricanes churning in the Atlantic Ocean, along with Helene and Isaac.

While Category 2 Helene is forecast to slide out to sea away from land, Category 1 Isaac is a threat the Caribbean later this week, according to the NHC.

Dangerous storms are also threatening parts of the United States in the Pacific Ocean.

Most of the state of Hawaii was under either a tropical storm warning or watch on Monday morning, as Hurricane Olivia is approaching it with maximum sustained winds of 136 kph.

Olivia could weaken into a strong tropical storm within 48 hours, according to forecasters.