National Park Rescue director of conservation Dr Niall McCann told BBC News that the mass deaths were first brought to the government’s attention in early May by a group of ecologists.
"They spotted 169 [dead elephants] in a three-hour flight," Niall said, referring to a flight the conservationists took over the Okavango Delta – a vast inland river in northern Botswana.
"To be able to see and count that many in a three-hour flight was extraordinary. A month later, further investigations identified many more carcasses, bringing the total to over 350."
He added: "This is totally unprecedented in terms of numbers of elephants dying in a single event unrelated to drought."
While it remains unclear what led to the mass deaths, the Botswana government is reportedly testing samples from the elephant carcasses to help determine what happened.
Botswana has the largest number of elephants in Africa, but last year the government overturned a hunting ban on the mighty mammal, which was first introduced in 2014.
The nation holds a very special place in Harry and Meghan’s heart, and over the years the couple have actively been involved with charities to prevent elephants from being poached and killed.
Most recently, Meghan even narrated Disney’s new documentary, Elephant which was released by the entertainment giant's streaming service, Disney+ in early April.
Meghan's return to the acting world coincided with her shocking move to Hollywood with Prince Harry and their son, Archie Mountbatten-Windsor.
The couple had originally fled to Vancouver, Canada, where they planned to raise Archie in a normal environment, away for the spotlight, but later relocated to La La Land.