Officials estimate one quarter of homes in Florida Keys destroyed by Hurricane Irma

The death toll from Hurricane Irma on the United States mainland rose to 10 on Tuesday with six people killed in Florida, three in Georgia and one in South Carolina.

At least 38 have been killed in the Caribbean with catastrophic damage in the British and US Virgin Islands, Barbuda, Turks and Caicos and St. Martin/St. Maarten, the island territory split between France and the Netherlands. The UN is airlifting food and emergency supplies to the decimated islands.

Approximately 15 million people across Florida, Georgia, Alabama and South Carolina remained without on power Tuesday according to an estimate released by the Department of Homeland Security. Due to power outages, the Atlanta Public Schools canceled classes for 55,000 students again for Wednesday.

Utility providers expect that power will not be completely restored in eastern and southern Florida until the end of Sunday and not until September 22 on the western Gulf Coast, which bore the brunt of Irma’s winds. Millions will be left exposed to high humidity and heat as temperatures approached 90F (32C) Tuesday and are expected to remain in the high 80s for the rest of the week.

While significant damage and flooding has been reported across the entire state the storm brought the worst damage to the Florida Keys off the southern coast of the state. The Federal Emergency Management Agency (FEMA) estimates that one quarter of the homes on the island chain were destroyed and another 65 percent suffered significant damage.

Summerland, Cudjoe and Big Pine Keys east of Key West suffered the worst damage as Irma hit the area as a category 4 hurricane Sunday with sustained winds of 155mph. The hurricane produced a massive storm surge and knocked down trees and power lines.

Officials from Monroe County, which covers the Keys, warned those who had evacuated from areas south of Islamorada that they would be unable to return to their homes for several more days. South of Islamorada cell service has been mostly knocked out meaning those who stayed behind have been unable to communicate with friends and family.

Monroe County Emergency Management Director Martin Senterfitt described the situation on the islands Sunday night as a “humanitarian crisis.” It is estimated that as many as 10,000 of the Keys’ 80,000 residents remained behind during the storm.

The Upper Florida Keys, Key Largo, Tavernier and Islamorada were reopened to residents Tuesday morning as the Florida Department of Transportation continued inspections on a final few bridges connecting the lower keys to Key West.

Aerial photographs showed many homes in Lower Keys with their roofs torn off and that a significant number of cheaply constructed mobile and trailer homes were completely ruined, thrown from their weak foundations or blown apart by the wind.

There are an estimated 54,000 mobile homes in the state of Florida, often the most affordable housing option for low-income workers, retirees and vacationers. However, these homes provide little protection and are most susceptible to the catastrophic damage from hurricanes and tornadoes, which frequently hit Florida.

The Keys’ water and sewage system, which is fed from the Biscayne Aquifer, was knocked off line by the storm and is still not functioning properly. It could take weeks to restore regular water service to all of the islands. The Florida Keys Aqueduct Authority reported on its Facebook page Tuesday that much of the damage of the water system occurred when trees uprooted by the wind and storm surge pulled water lines out of the ground.

The situation was even worse for the islands’ electrical infrastructure with at least 200 power line poles downed or damaged, which now need to be restored. Monroe County Commissioner Heather Carruthers told MSNBC it would take as long as a month to restore full power to the Lower Keys.

The Pentagon reported on Tuesday it would be necessary to evacuate those who remained on the islands if essential services were not restored quickly. The USS Abraham Lincoln aircraft carrier has been moved into position to assist with evacuations and deliver food and water to survivors.

Meanwhile in the state’s far northeast, the port of Jacksonville, which processes more than 1 million containers and 630,000 automobiles each year, was set to reopen today after being closed since Saturday. The city of Jacksonville experienced some the worst flooding in its history as storm surge flooded the Saint Johns River.

The port of Tampa Bay reopened Tuesday afternoon allowing 10 tanker ships to deliver nearly 10 million gallons of gasoline desperately needed to power generators and vehicles. Port Everglades near Fort Lauderdale reopened to cruise ships on Tuesday, with three ships arriving carrying a total of 12,000 passengers.