Hurricane Irma made landfall in Florida on Sunday after leaving at least 27 dead since the now Category 4 storm (with sustained winds up to 209km/h) first hit many Caribbean islands last week, authorities of the US state announced.

A sudden shift in the trajectory of the storm, the eye of the hurricane is now expected to touch land not in Miami but in Florida Keys in the far south, moving towards Naples, Fort Mayers and the Tampa Bay on the west coast.

This has made evacuation and other preparations challenging, according to the National Hurricane Centre (NHC).

Residents of mainland Florida are bracing for Hurricane Irma to hit, as conditions in the south of the state deteriorate, reported BBC.

High winds and storm surges are affecting the Miami area, but Florida Governor Rick Scott said he was "very concerned" about the west coast.

As the eye of the storm is moving north to mainland Florida, more than a million homes in the state are reported to be without power and some 50,000 people have taken refuge in shelters.

Cities such as Tampa and St Petersburg lie in the path of the storm. The Tampa Bay area, with a population of about three million, has not been hit by a major hurricane since 1921, stated the BBC report.

More than 6.3 million people in Florida were told to evacuate, with warnings of a "life-threatening" storm surge.

One official had warned staying on the islands would be "almost like suicide".

Media reports say a man was killed on Saturday in the Keys when his pick-up truck crashed into a tree as the storm gathered pace.