The most powerful storm to hit the Bahamas since records began has torn off roofs and caused severe flooding.
The slow-moving, category five Dorian – the second-strongest Atlantic hurricane on record – is now packing sustained winds of up to 165mph (270km/h) and may cause a storm surge of up to 23ft (7m).
There is no official word on casualties but the Red Cross fears some 13,000 homes have been damaged or destroyed.
The hurricane is moving slowly west, with the eastern US coast at risk.
The US states of Florida, Georgia, North and South Carolina have all declared states of emergency.
According to reports Dorian was moving very slowly through Grand Bahamas, having made landfall earlier on the Abaco islands, which are just to the east.
Both chains are in the north of the Bahamas archipelago. Grand Bahama, with a population of about 50,000, is only 100km (60 miles) east of West Palm Beach in Florida.
Dorian is travelling west at just over 1mph (2km/h).