A 90-year-old woman who was found dead in a South Carolina pond after disappearing from her assisted living home was killed by an alligator, officials said Wednesday. 

The Charleston County Coroner's Office ruled that Bonnie Walker's death was accidental and caused by "multiple sharp and blunt force injuries". The state's Department of Natural Resources said it had conducted a necropsy on the alligator and confirmed it was involved in Walker's death. 

Walker was reported missing from the Brookdale Senior Living Center in Charleston Wednesday morning. Her body was found in a retention pond behind the property a little more than three hours later. 

Charleston County Coroner Rae Wooten said in a statement that investigators believe Walker slipped or fell into the pond, which drew the alligator's attention. 

State Department of Natural Resources spokesman Robert McCullough told the Post and Courier newspaper that the case was the first alligator-related fatality on record in the state. 

Brookdale issued a statement saying they extended their deepest sympathies to Walker's family and are helping the investigation into her death. It was not immediately clear how Walker was able to leave the facility. 

The Associated Press contributed to this report.