The Lion Country Safari said in a Facebook post that recent pathology results confirmed that the giraffes, named Lily and Jioni, died as a result of a lightning strike and the deaths were "instantaneous."
"The giraffes do have access to numerous shelters in the multi-acre habitat, if they choose to use them," the park said in its Facebook post. "The keepers and our whole team were understandably devastated by this sudden and tragic loss; out of respect for their mourning and the pending pathology results, we waited to share this information."
Lion Country Safari calls itself a cageless zoo and is the only drive-through safari in south Florida, with 320 acres of land and more than 1,000 animals, according to FOX35.
The park breeds a number of a rare or endangered species, including giraffes, through the Association of Zoos and Aquarium's Species Survival Plan.
Park spokesperson Haley Passeser told WPTV the facility has a lightning detection system, and when the storm rolled through, officials opened up the animal shelter area under the standard protocol.
"We do try to provide them a lot of choice, and in a case such as that when we ourselves are also seeking shelter," Passeser told the television station. "If they don’t choose to seek shelter, there isn’t a lot we can do to encourage them to."
Passeser said that the safari is now reviewing its policies and procedures after the incident, which reportedly led to some animal keepers taking "personal time off to process" the events.
"It was just very tragic, natural effect, natural accident, and it was very devastating to our staff and we are still mourning from it," she told WPTV.
The Sunshine State had the highest density of lightning strikes in 2018. Florida had the highest average of negative ground-to-cloud flasher per square mile, with 24, according to a study released earlier this year from environmental measurement specialist Vaisala.
Lighting typically strikes tall objects such as trees and skyscrapers because their tops are closer to the base of the storm cloud, according to The National Severe Storms Laboratory.
"However, this does not always mean tall objects will be struck. It all depends on where the charges accumulate," according to the agency. "Lightning can strike the ground in an open field even if the tree line is close by."
Lightning known as a "bolt from the blue" can also strike from as far away as 25 miles away from a thunderstorm cloud, even when there appear to be clear skies, according to the NSSL.
"They can be especially dangerous because they appear to come from clear blue sky," the agency states.
Fox News' James Rogers contributed to this report.