MIAMI, United States (AFP) — Four employees of a nursing home in the US state of Florida have been charged with aggravated manslaughter for the deaths of 12 residents under their care after Hurricane Irma in 2017, police said.

The elderly retirees at the facility north of Miami died after temperatures reached intolerable levels at the facility, where the air condition system failed during the storm.

“This was a terrible tragedy that should have never happened,” Hollywood, Florida police chief Chris O’Brien said.

The nursing home’s manager and a night nurse was arrested and charged with aggravated manslaughter, while two other nurses were charged with aggravated manslaughter and evidence tampering.

“These individuals took an oath to provide care and safety for these individuals in their facility,” O’Brien said. “They betrayed that oath.”

Residents remained in deteriorating conditions for three days after Irma, according to authorities at the hospital where they were later transferred, and most suffered from respiratory distress, dehydration and heat-related issues.

Eight of the victims were between 71 and 99 years old.

Governor Rick Scott of Florida, the warm southern state home to a large population of retirees, called the episode “unfathomable” at the time and ordered an investigation after closing the facility, where some 100 people lived.