(CNN) Claire Frank has not heard from her two daughters since late Tuesday night, an hour before electrical power was cut in the tiny Caribbean island of Barbuda, some 1,200 miles southeast of Miami.

With Hurricane Irma approaching at the time, Afiya Frank, 27, who is pregnant, and sister Asha, 29, had packed plenty of food and water and boarded up the large brick house their family had nearly completed on the 62-square-mile island.

"Everybody knew it was a superstorm," Claire Frank said on the phone from the United Kingdom.

"When it's your children, you don't want to frighten them to death but you want them to know that they have to know what to do."

Frank may have gotten news about one of her daughters late Thursday but she's still uncertain. It came in a Facebook post in which a stranger on the island wrote, "I saw the Asha Frank girl ... She all good. Running things."

"I'm not going to say I know my daughters are safe until I've heard about it from the people organizing the evacuation," said Frank, referring to the voluntary evacuation of the island on Thursday as another hurricane approached.

About 95% of the buildings in Barbuda, one of two major islands in the nation of Antigua and Barbuda, are damaged, Prime Minister Gaston Browne said.

Asha Frank is 29 and has been through Hurricane Luis in 1995.

While still assessing the extent of Irma's destruction, the northeastern Caribbean islands anxiously watched Hurricane Jose to the east. Antigua and Barbuda issued a hurricane watch for Jose, which could pass close on Saturday.

Irma left at least six people dead, including four on St. Martin, one on Anguilla, and one on Barbuda, officials said.

Irma has left Barbuda -- a quiet, underdeveloped oasis with some high-end tourism -- barely habitable.

"It's like a deserted island," said Michael Joseph, president of Red Cross in Antigua and Barbuda.

Tourism dominates Antigua and Barbuda's economy, accounting for nearly 60% of GDP and 40% of investment, according to the CIA World Factbook.

Amy Potter, a geography professor at the Armstrong State University in Georgia, said the economy of Barbuda -- one of the lowest lying islands in the Caribbean -- relied heavily on sand mining operations for more than 30 years despite warnings about the island's vulnerability to major storms.

Afiya Frank, 27, is pregnant. Her mother spoke to both daughters before Hurricane Irma hit.

"Any time you have dunes, that's a very important protection," said Potter, a Savannah resident who was preparing to evacuate as Irma neared the US coast. "Dunes and mangroves provide really important buffers for low-lying islands during hurricanes."

Andrew Sluyter, a professor at Louisiana State University in Baton Rouge, said fraught relations between Antigua and the smaller island of Barbuda could worsen after the disaster.

"I can tell you that the minute I heard that Barbuda had 95% of its houses destroyed and Antigua very little damage, I started thinking about how that would impact their relationship," he said via email.

"Any help Antigua provides to rebuild Barbuda will no doubt come at a steep price in terms of allowing tourist development."

Frank said her daughters had already lived through the deadly and destructive Hurricane Luis in 1995, which packed sustained winds of 140 mph.

But Irma, a Category 5 storm, churned in the Atlantic with 175 mph sustained winds.

"It's not in their kind of recent memory but they do know what you would need to do," Frank said, recalling Tuesday's chat with her daughters via a messaging app.

"They said in an hour or so they'll turn off the electricity. We just said, 'Bye. We'll speak to you soon.' I haven't heard from them since."

Frank was upset that Browne has been widely available to the international media in the storm's aftermath but that she has not been able to get information from the local government.

"Unfortunately the Prime Minister has made himself the spokesman of this event and hasn't given any information to people about who they could speak to" for information about survivors, she said.

Browne could not be reached for comment.

Frank, a UK native, has lived in Barbuda about 30 years. She runs ArtCafe, a cafe and art gallery where she sells silk paintings and handpainted T-shirts. She said she has about four customers a month. She met her husband, a Barbudan, in the United Kingdom.

Frank's daughters grew up on the island but studied in the United Kingdom because Barbuda did not have a secondary school when they were ready for high school, she said.

"Barbuda is a bit of a brain drain," Frank said.

"People leave and they don't come back because there is nothing for them to come back to. We've always believed that young age group of people will make a difference. They will have skills. They will develop businesses and then Barbuda will stop being this kind of backwater to Antigua."