'Screaming' Hurricane Maria makes landfall in Puerto Rico

It is the strongest storm to hit the Caribbean island since 1932. And it is the second monster storm to smash into the Caribbean in a fortnight, packing highly dangerous sustained winds of 155mph.

Currently a category four storm, it is heading to San Juan — where the bulk of the population is hunkered down.

"The wind sounds like a woman screaming at the top of her lungs!" photographer and storm chaser Mike Theiss posted on Twitter.

The life-threatening winds are expected to batter Puerto Rico for up for 24 hours.

"This is going to be an extremely violent phenomenon," governor Ricardo Rossello said. "We have not experienced an event of this magnitude in our modern history."

English tourist Mary Pires told Puerto Rican media: "I do not even want to imagine what's coming in. They all tell me it's the worst."

Roofs are flying through the streets and windows are smashing. Nearly 900,000 people have already lost power in their homes.

The storm is moving northwest and its path will take it over the already devastated Virgin Islands and up through the Turks and Caicos Islands. The British government is warning people to stay away from the region.

Sky News' Mark Austin is in Puerto Rico. As the storm made landfall, he said: "There is debris flying through the air, there are bins… we've seen trees broken off, and balconies broken off and these are substantial buildings."

Austin added: "There are still many people here. There are about 500 shelters — I pray that people are in them."

As Maria approached, US President Donald Trump tweeted: "Puerto Rico being hit hard by new monster

Hurricane. Be careful, our hearts are with you — will be there to help!"