Deadly hurricane Matthew bearing down on Florida, Georgia

Matthew, the first major hurricane threatening a direct hit on the United States in more than 10 years, blasted the Bahamas on Thursday as it headed for Florida after killing at least 265 people in the Caribbean, mostly in Haiti.

Carrying extremely dangerous winds of 140 mph (220 kph), the storm pounded the northwestern part of the Bahamas en route to Florida's Atlantic coast, the US National Hurricane Center (NHC) said.

US President Barack Obama declared a state of emergency in Florida as Matthew strengthened, the White House said on Thursday.

The action authorizes the Department of Homeland Security and the Federal Emergency Management Agency to coordinate disaster relief efforts necessitated by the storm, a Category 4 hurricane packing winds of 140 mph (220 kph).

"Hurricane Matthew is as serious as it gets. Listen to local officials, prepare, take care of each other," Obama warned people in the path of the storm in a posting on Twitter.

Matthew's sustained winds later dropped to 130 mph, but it was likely to remain a Category 4 on the five-step Saffir-Simpson scale of hurricane intensity as it closed in on the United States, where it could either take direct aim at Florida or tear along the state's coast through Friday night, the Miami-based center said.

Few storms with winds as powerful as Matthew's have struck Florida, and the NHC warned of "potentially disastrous impacts". The US National Weather Service said the storm could be the most powerful to strike northeast Florida in 118 years.

Hurricane conditions were expected in parts of Florida late on Thursday and a dangerous storm surge is expected to reach up to 11 feet (3.35 meters) along the Florida coast, Ed Rappaport, deputy director of the Miami-based NHC, said on CNN.

"What we know is that most of the lives lost in hurricanes is due to storm surge," he said.

Some 260 people were killed in Haiti, local officials said, and thousands were displaced after the storm flattened homes, uprooted trees and inundated neighborhoods earlier in the week. Four people were killed in the Dominican Republic, which neighbors Haiti.

As the storm passed near the Bahamas capital of Nassau, howling gusts of wind brought down palms and other trees and ripped shingles off the rooftops of many houses. The eye of the storm was located over the western end of Grand Bahama Island on Thursday evening.

It was too soon to predict where Matthew might do the most of its damage in the United States, but the NHC's hurricane warning extended up the Atlantic coast from southern Florida through Georgia and into South Carolina. More than 12 million people in the United States were under hurricane watches and warnings, according to the Weather Channel.

The last major hurricane, classified as a storm bearing sustained winds of more than 110 mph, to make landfall on US shores was Hurricane Wilma in 2005.

Florida Governor Rick Scott warned there could be "catastrophic" damage if Matthew slammed directly into the state, and he urged some 1.5 million people there to evacuate.

"If you're reluctant to evacuate, just think about all the people ... already killed," Scott said at a news conference. "Time is running out. This is clearly either going to have a direct hit or come right along the coast."

Scott, who activated several thousand National Guard troops, warned that millions of people were likely to be left without power.

Florida, Georgia and South Carolina opened shelters for evacuees. As of Thursday morning, more than 3,000 people were being housed in 60 shelters in Florida, Scott said.