LOWER MATECUMBE KEY, Fla. — Search-and-rescue teams made their way into the Florida Keys’ farthest reaches Tuesday, while authorities rushed to repair the lone highway connecting the islands and deliver aid to Hurricane Irma’s victims. Federal officials estimated one-quarter of all homes in the Keys were destroyed.

Two days after Irma roared into the island chain with 130 mph winds, residents were allowed to return to the parts of the Keys closest to Florida’s mainland.

But the full extent of the death and destruction there remained a question mark because cellphone service was disrupted and some places were inaccessible.

“It’s going to be pretty hard for those coming home,” said Petrona Hernandez, whose concrete home on Plantation Key with 35-foot walls was unscathed, unlike others a few blocks away. “It’s going to be devastating to them.”

Elsewhere in Florida, life inched closer to normal, with some flights again taking off, many curfews lifted and major theme parks reopening. Cruise ships that extended their voyages and rode out the storm at sea began returning to port with thousands of passengers.

The number of people without electricity in the steamy late-summer heat dropped to around 10 million — half of Florida’s population. Utility officials warned it could take 10 days or more for power to be fully restored. About 110,000 people remained in shelters across Florida.

The number of deaths blamed on Irma in Florida climbed to 12, in addition to four in South Carolina and two in Georgia. At least 37 people were killed in the Caribbean.

“We’ve got a lot of work to do, but everybody’s going to come together,” Florida Gov. Rick Scott said. “We’re going to get this state rebuilt.”

In hard-hit Naples, on Florida’s southwest coast, more than 300 people stood outside a Publix grocery store in the morning, waiting for it to open.

A manager came to the store’s sliding door with occasional progress reports. Once he said workers were throwing out produce that had gone bad, another time that they were trying to get the cash registers working.

One man complained loudly that the line had too many gaps. Others shook their heads in frustration at word of another delay.

At the front of the line after a more than two-hour wait, Phill Chirchirillo, 57, said days without electricity and other basics were beginning to wear on people.

“At first it’s like, ‘We’re safe, thank God.’ Now they’re testy,” he said. “The order of the day is to keep people calm.”

Irma’s rainy remnants, meanwhile, pushed through Alabama and Mississippi after drenching Georgia. Flash-flood watches and warnings were issued around the Southeast.

Federal Emergency Management Agency administrator Brock Long said that preliminary estimates suggested that 25 percent of the homes in the Keys were destroyed and 65 percent sustained major damage.

“Basically every house in the Keys was impacted,” he said.

In Islamorada, a trailer park was devastated, the homes ripped apart as if by a giant claw. A sewage-like stench hung over the place.

Debris was scattered everywhere, including refrigerators, washers and dryers, a 25-foot fishing boat and a Jacuzzi. Homes were torn open to give a glimpse of their contents, including a bedroom with a small Christmas tree decorated with starfish.

One man and his family came to check on a weekend home and found it destroyed. The sight was too much to bear. The man told his family to get back in the car, and they drove off toward Miami.

In Key Largo, Lisa Storey and her husband said they had yet to be contacted by the power company or by city, county or state officials. As she spoke to a reporter, a helicopter passed overhead.

“That’s a beautiful sound, a rescue sound,” she said.

An aircraft carrier was positioned off Key West to help in the search-and-rescue effort. And crews worked to repair two washed-out, 300-foot sections of U.S. 1, the only highway from the mainland, and check the safety of the 42 bridges linking the islands.

Authorities stopped people and checked for documentation such as proof of residency or business ownership before allowing them back into the Upper Keys, including Key Largo, Tavernier and Islamorada.

The Lower Keys — including the chain’s most distant and most populous island, Key West, with 27,000 people — were still off-limits, with a roadblock in place where the highway was washed out.