The victims were five women and three men who ranged in age from 71 to 99, according to local authorities.
The deaths at the facility in Hollywood, just north of Miami, drew outrage across a state with a large population of seniors — and where hundreds of thousands remain without electricity as a result of the hurricane that swept across the state beginning Sunday.
Many Florida residents lacking electricity in their homes have moved in with friends or relatives or sought hotels with air conditioning as temperatures soared above 90 degrees.
Meanwhile, a number of other post-hurricane deaths were reported from a variety of factors, including toxic fumes from generators and at least one fatal chain-saw accident as residents sought to clear storm-blow brush from their properties.
Authorities said a criminal investigation had begun after more than 100 patients were evacuated from the Hollywood nursing home and a neighboring facility, many on stretchers and in wheelchairs.
“I’m going to aggressively demand answers on how this tragic event took place,” Florida Gov.
The deaths at the nursing home, known as the Rehabilitation Center at Hollywood Hills, may have been related to the loss of air conditioning, Hollywood Police Chief Tomas Sanchez told reporters.
"We believe at this time they may be related to the loss of power in the storm," he said. "We're conducting a criminal investigation, not ruling anything out at this time."
The air conditioning at the facility was out, Sanchez said, but it remained under investigation whether power was entirely cut. He declined to answer when asked if a generator had been running inside.
Yellow police tape cordoned off the two-story, 152-bed nursing home where police and media satellite trucks parked outside.
The facility is across the street from the sprawling Memorial Hospital complex, which reportedly did not suffer electrical outages.
Three patients were found dead at the nursing home early Wednesday, according to various accounts, and the others apparently succumbed later after being evacuated to area hospitals.
The deaths spurred new concern for the effects of widespread power outages in a state that has one of the highest proportions of senior residents in the United States.
Authorities said they were moving to check that other nursing homes and elderly-care facilities were safe.
About 150 of the almost 700 nursing homes and other care facilities in Florida do not currently have full power, the Florida Health Care Assn., an industry group, said in a statement Wednesday.
The nursing home where the deaths occurred issued a statement lamenting "this unfortunate and tragic outcome," which it said was the result of "a prolonged power failure to the transformer which powered the facility's air conditioning system as a result of the hurricane." The facility's administration said it was "cooperating fully" with local authorities in their investigation.
A Medicare agency inspection of the Rehabilitation Center this year found a number of problems, including inadequate communication systems in showers and bathrooms, improper disposal of garbage, a failure to handle linens in a manner to prevent the spread of infection, a failure to ensure that patients were being fed proper portions of food, and a failure to "store, cook and serve food in a safe and clean way."
The report did not mention the generator or potential problems with electrical outages.
The nursing home's current ownership group took over in 2015 in bankruptcy auction proceedings after the previous majority owner was convicted in a Medicare fraud scheme.
Sen. Bill Nelson (D-Fla.) said he is asking the secretary of Health and Human Services to look into what happened.
State law mandates that nursing homes have emergency preparation plans in place — including emergency power options — for natural disasters. Industry representatives said they were taking additional steps to ensure safety in the wake of the storm.
In Miami-Dade County, nearly 442,000 of its 1.1 million customers had outages, according to Florida Power & Light. In Broward County, 300,000 were without power, and in Palm Beach County about 260,000 outages were reported, according to the company. Florida Power & Light estimates it will restore power to all of its customers in South Florida by the weekend.
Rising temperatures and a lack of power have made it difficult for seniors and children in the days since Irma. Officials from the Miami-Dade Public School District said schools would remain closed the rest of the week because of power issues.
The continued lack of power in South Florida has forced people to change their lifestyles and, in some cases, to find alternative short-term housing.
"It's just been very hard, especially for our son," said Yulayki Guillen, 24, who found a hotel in downtown Miami along with her husband, mother and 5-year-old son, Luis.
The family spent Tuesday night in the hotel, paying about $200, after several difficult evenings without electricity in their condominium north of downtown.
"Our son was very uncomfortable — he couldn't sleep, he was sweating, and he was out of his routine," said Guillen, sitting in the lobby of the hotel with her family. "So we decided to come here. At least there's air conditioning. Luis likes it here. He wants to stay."
Food is another issue. Many stores remain closed because of the lack of electricity, meaning people are converging on the relatively few shops and eateries that are open. Waits are often considerable.
"Even to get fast food at a Burger King or McDonald's, there was a line around the corner," Guillen said.
Since Irma made landfall on Sunday, 13 people in Florida were killed in storm-related circumstances — in some cases during the cleanup efforts — in addition to those who died at the nursing home. Elsewhere, Irma was blamed for four deaths in South Carolina and two in Georgia. At least 37 people were killed in the Caribbean.
McDonnell reported from Hollywood, Fla., and Lee from Los Angeles. Times researcher Scott Wilson in Los Angeles contributed to this report.
4:50 p.m.: This article was updated with additional details.
2:15 p.m.: This article was updated with a new death toll, which rose to eight.
1:35 p.m.: This article was updated with pertinent state regulations for nursing homes and comments from an advocacy group for the elderly.
11:45 a.m.: This article was updated with comments from Florida Gov. Rick Scott and information about hospitalized patients.
9 a.m.: This article was updated throughout with staff reporting and additional details, including a report of a sixth death at the Hollywood, Fla., nursing home.