15 elephants near Amboseli National Park died in one month from suspected cyanide poisoning, according to the Kenya Wildlife Service (KWS)
The wildlife authority said preliminary laboratory analysis picked up traces of cyanide in the elephants' bodies
The KWS has since increased park surveillance across the park and ecosystem
Fifteen elephants are believed to have been killed by cyanide-contaminated tomatoes in southern Kenya.
The animals roamed near the Amboseli National Park, which borders a farming and livestock area around 140 miles south of the capital Nairobi, according to the Associated Press.
Authorities did not provide any information on the source of the cyanide contamination, but it's believed that farming pesticides may be a likely cause, reported the BBC. Authorities currently do not suspect foul play, the outlet added.
The Kenya Wildlife Service (KWS) director general, Erastus Kanga, said preliminary laboratory analysis of the elephants' bodies picked up traces of cyanide, which he described as a "highly toxic chemical, particularly for elephants," per the AP and local outlet Citizen Digital.
"Environmental investigations are also being undertaken, including the analysis of water sources and other potential environmental contaminants within the affected areas, to establish whether the elephants were exposed to a common source," the KWS added, per The Guardian.
"Other than the elephants and the wildlife that may be feeding in those fields, we have the local livestock. We have the goats. We have the cattle that are there. Eventually, if this is truly what is in the system, then we are going to see a bigger impact," Kanga added to the AP.
The BBC reported that ten of the elephants died two days after veterinarians noticed signs of paralysis in the animals. The other five were found dead in a state of decomposition, the KWS said, per The Guardian.
The deaths happened between June 24 and July 24, the BBC reported.
KWS's head of veterinary and capture services, Dr. Isaac Lekoolol, told Citizen Digital that the animals all showed similar symptoms before dying.
He added that the KWS had managed the situation, but warned those living around Amboseli National Park and nearby wildlife conservancies to take care when using agricultural chemicals, per the outlet.
The agency said it has upped surveillance across the park and is closely monitoring elephant herds while investigations continue. The substance thought to be found in the dead elephants poses no immediate threat to humans.
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Around 2,000 elephants roam wild in the Amboseli National Park, per the Amboseli Trust for Elephants.
The location is one of a few that is free of poaching and culling, with elephant living from "birth to extreme old age," according to the Trust.
"Elephants communicate at a very sophisticated level, they celebrate birth, have lifelong friendships and mourn the death of friends and family members. They are highly intelligent animals with the ability to reason and problem solve, and they live their lives inside a complex social structure," the Trust added.
The KWS did not immediately respond to PEOPLE's request for further information.
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