TITUSVILLE, FLORIDA - Hurricane Dorian battered the Bahamian islands of Great Abaco and Grand Bahama early on Monday, peeling off roofs, toppling cars and snapping power lines as rising floodwaters threatened to engulf houses.

The second-strongest Atlantic storm on record was forecast to keep pounding the archipelago through the day, then move towards the east U.S. coast - where authorities ordered more than a million people evacuated in Florida, South Carolina and Georgia.

The slow-moving, category five storm left the islands covered with twisted metal and splintered wood.

Winds gusting up to 200 mph destroyed or damaged more than 13,000 homes, the International Federation of Red Cross and Red Crescent Societies said.

Residents posted images online of water rising up the sides of their houses as the National Hurricane Center warned of a possible storm surge of of 18 to 23 feet above normal tide levels, with higher destructive waves, which is higher than many roofs on the islands.

Residents said effects were already felt in Florida with high surfs, riptides and storm warnings up and down the Atlantic coast.

As of 5 a.m., Dorian was stalled atop the Grand Bahama Island barely drifting westward at 1 mph, even as it packed winds of 165 mph with gusts upward of 200 mph, the in Miami (NHC) said.

Residents on Abaco posted video on social media showing floodwaters halfway up the sides of single-family homes and the island was littered with twisted metal and splintered wood.

Dorian was expected to linger over the Bahamas for most of Monday if not longer, forecasters said.

The federation also said that water supplies were likely contaminated with seawater, making relief efforts all the more urgent.

At 5 a.m. (0900) GMT on Monday, the hurricane was about 125 miles from the Florida coast, parts of which were being evacuated, as it crawled westward. Farther north, South Carolina Governor Henry McMaster ordered mandatory evacuations for parts of eight coastal counties effective at noon (1600 GMT) on Monday.

Georgia Governor Brian Kemp ordered evacuations in all or parts of six coastal counties also effective at noon on Monday.

Even a glancing blow from one of the strongest storms ever to menace Florida could bring torrential rains and damaging winds, the NHC said.

"The hurricane will move dangerously close to the Florida east coast late Monday through Tuesday night," the NHC said. -Reuters