The centre of Hurricane Irma has hit mainland Florida, just south of Naples, amid warnings of storm surges as high as 15ft (4.5m).

Irma made landfall on Marco Island off Florida's west coast with winds of up to 105mph (169km/h) but has since been downgraded to a category two storm.

More than 2.5 million homes in the state are without power, and parts of the city of Miami are under water.