Police obtained a search warrant on Thursday in their criminal investigation of the deaths of eight elderly patients exposed to sweltering heat inside a Miami-area nursing home that continued to operate with little or no air conditioning after Hurricane Irma struck.

The loss of life at the nursing home in Hollywood, Florida, brought the overall death toll from Irma to 81, with several hard-hit Caribbean islands including Puerto Rico and the U.S. Virgin Island, accounting for more than half the fatalities.

Irma, which had ranked as one of the most powerful Atlantic storms on record before striking the U.S. mainland as a Category 4 hurricane, has been blamed for at least 31 deaths in Florida, plus seven more in Georgia and South Carolina, combined.

The eight deaths at the Rehabilitation Center at Hollywood Hills, days after Irma struck, stirred outrage at what many saw as a preventable tragedy, and heightened concerns about the welfare of the state's large elderly population with 2.8 customers still without electricity.

"It was unnecessary," Bendetta Craig, whose 87-year-old mother was among dozens of patients safely removed from the centre, told reporters on Thursday. "I don't know what happened inside. I wasn't there. I hope the truth comes out. It is just senseless."

The facility was is just one of nearly 700 nursing homes across the state, about 150 of which still lacked power as of Wednesday morning when the Hollywood Hills crisis occurred, according to the Florida Health Care Association.

Police, assisted in their investigation by state and federal regulators, have said little about circumstances leading to the deaths of the patients ranging in age from 71 to 99.

At Thursday's news conference, medical workers from an adjacent hospital who assisted in evacuating the centre on Wednesday recounted a scene of chaos and stifling conditions as panicky staff scrambled to move overheated patients into a room where fans were blowing.

Facing a situation that was out of control, doctors and fire officials ultimately decided to transfer all the patients to the hospital, where dozens were treated for respiratory distress, dehydration and heat exhaustion, officials said.

Of the 141 patients who were evacuated, 70 were discharged from the hospital as of Thursday, city officials said.

Craig said nursing home staff had assured her before the storm that they were prepared to safely shelter residents through the hurricane, and were equipped with generators, food and other necessary supplies.

She questioned whether short staffing and fatigue on the part of overworked personnel may have factored in the crisis.

Attempts by Reuters to reach representatives of the for-profit nursing home by phone and email went unanswered.

The centre, which police sealed off as a crime scene on Wednesday, was officially ordered closed to new admissions by the state's Agency for Health Care Administration.

The facility has had a spotty inspection record, earning a “below average” grade Medicare’s nursing home rating system. The state health care agency listed the centre as among the lowest-ranked 20 percent of all nursing homes in Broward County.

A state inspection report in February 2016 cited the facility for failing to comply with regulations for emergency generators. There was no indication from state records of follow-up action on the issue, and no such deficiency was cited in fire-life safety inspection conducted a few months ago.

The physician listed in state records as the nursing home's manager, Dr. Jack Michel, ran afoul of state and federal regulators in 2004 over a hospital and group of assisted-living facilities he partially owned. In 2006, he and three co-defendants paid $15.4 million to settle Medicare and Medicaid fraud claims against them without admitting wrongdoing.

VISIT BY TRUMP

U.S. President Donald Trump paid a visit on Thursday to Gulf Coast Florida communities recovering from the hurricane, praising first-responders for their role in limiting the toll taken on human lives.

"When you think of the incredible power of that storm, and while people unfortunately passed, it was such a small number," Trump said. "People thought thousands and thousands of people may have their lives ended and the number is a very small number, which is a great tribute to you."

Florida officials including Governor Rick Scott and U.S. Senator Marco Rubio greeted Trump and Vice President Mike Pence in Fort Myers, Florida.

The president, wearing a white baseball cap with "USA" written on it, later visited Naples, where he handed out sandwiches to residents under a blue shade pavilion.

Irma rampaged through the Caribbean, devastating several islands and raking the northern shore of Cuba last week before barrelling into the Florida Keys island chain on Sunday, packing sustained winds of up to 130 miles per hour (215 km per hour).

An estimated 20 percent of Florida's gas stations had no fuel on Thursday, down from a peak of 46 percent, according to fuel information service Gas Buddy.