Richard Branson, son promote relief effort for Caribbean after Hurricane Irma Branson and his son decided to stay on a private island during the storm.

 -- Richard Branson's son Sam Branson took to Instagram Thursday to promote a relief effort to help those in the Caribbean islands that were and continue to be affected by Hurricane Irma.

"#hurricaneirma relief @britishredcross relief fund has been set up. Please donate all you can to help those who have lost everything. Every little will help! @virgin_money_giving are waving their fee's so all funds can go to the front line to help where it is needed the most!" Sam Branson posted on Instagram earlier today.

His father, Richard Branson, also announced that his company Virgin Group has donated to the effort.

"@virginunite have donated to @britishredcross appeal to provide aid, @virginatlantic flight to help recovery. Urge everyone to donate & support any way they can," he wrote.

The relief effort comes a day after Sam Branson posted pictures and videos from the aftermath of Irma on his father's private island in the Caribbean. He was able to announce that "all humans on Necker [Island] are ok although a lot of buildings destroyed."

The elder Branson had written on his company's website earlier in the day that he and a group of people would remain on Necker Island and planned to retreat to a concrete wine cellar under his home when the storm struck.

Sam Branson wrote in one of his posts, "Very concerned for our friends and everyone on the neighbouring islands and people in its path. Please don't take this hurricane lightly if it is heading your way. If your building is not very solid, do find somewhere safe! Homes can be rebuilt but lives can't."

His photos show the destruction of other BVI islands like Tortola, where most of the buildings have been destroyed.

He also shared a heartbreaking video that he called "Beyond tragic. My deepest wishes go to all those affected." Sam Branson seems to have been sourcing the videos and pictures from neighboring islands.

The Category 5 storm, with maximum sustained winds of 180 mph as of 5 a.m. Thursday morning, destroyed about 95 percent of structures and vehicles on the island of Barbuda Wednesday afternoon, according to Antigua and Barbuda Prime Minister Gaston Browne. In total, at least 13 people have been killed in the Caribbean.

"Everyone is willing the eye of the storm to veer away from the BVI in these last few hours," Richard Branson wrote before the storm hit Necker Island. "As I wrote yesterday, our main concern is safety, for everyone here and for all the people in the BVI and in the path of the hurricane."

On Tuesday, Richard Branson wrote that buildings on the island are "really strong" and have hurricane blinds, which enables them to "handle extreme weather pretty well." This will be the third hurricane he has weathered on Necker Island, he wrote. On Tuesday, he and those with him played Perudo and slept together in two rooms.

"I haven't had a sleepover quite like it since I was a kid," he wrote. "Strangely, it's a privilege to experience what is turning into possibly the strongest storm ever with such a great group of young people."