Hurricane-scarred Florida warily eyed the fate of its most vulnerable residents and emergency workers were urged to immediately check on those in nursing homes after eight people died in a scorching facility that lost its air conditioning in the storm.
Broward County Mayor Barbara Sharief told NBC Miami that three people died at the facility and the other two died as the patients arrived at the hospital. Five others died in hospital.
Irma is now tied as the second-strongest Atlantic hurricane, according to the National Hurricane Center.
Irma killed at least 31 people in Florida, plus seven more in Georgia and SC combined, authorities said.
The deaths at the Rehabilitation Center at Hollywood Hills, now under police and state investigation, stirred outrage over what many saw as a preventable tragedy and heightened concerns about the vulnerability of the state's large elderly population amid widespread, lingering power outages.
Florida Gov. Rick Scott has said that restoring power to hospitals and nursing homes was a priority.
"This situation is unfathomable", he said.
Emergency services were called to the scene on Wednesday morning after some residents awoke sick.
Temperatures on Tuesday in Hollywood reached 32C (90F), according to the National Weather Service.
Across the street from the stifling nursing home sat a fully air-conditioned hospital, Memorial Regional.
Irma, categorised as one of the most powerful Atlantic storms on record when it rampaged through the Caribbean, has killed at least 77 people, including over 20 in the United States.
"Here is one of several, up to 30, or so drone operators that are helping ups to asses the damage and ultimately the damage we need to overcome to get the lights back on", said Jose Labrador, FPL.
Assisted living facilities across the state serve an additional 92,000 residents.
"Approximately 150 facilities out of the almost 700 (nursing) facilities in the state do not now have full power services restored", the statement said.