A truck carrying 100 lab monkeys crashed in Pennsylvania.
Several of the primates escaped shortly after the vehicle collided with a pick-up truck in Danville on Friday (November 21), which sparked a large-scale rescue operation to find them all.
Officials managed to rustle up the majority of the cynomolgus macaque monkeys, however one remained unaccounted for.
The Pennsylvania Game Commission, other agencies, and even residents in the area braved the freezing temperatures to find the final animal.
They searched in nearby forests and through every residential nook and cranny for the monkey.
Local Nate Allen told news station WKBN27: "We just decided to come and try, see if we could find one.
"I saw it on Facebook, and actually this started as kind of a family fun joke about just making an experience and going to try and save a monkey, so I actually brought a kennel, flashlights, night vision goggles."
Police urged residents to avoid joining in on the search as animal rescue can be a fairly hectic process.
"Anyone who sees or locates the monkey is asked not to approach, attempt to catch, or come in contact with the monkey. Please call 911 immediately," authorities tweeted.
Firefighters were called in for the search and they used thermal imaging to find the animal while a helicopter circled overhead to see if it could spot it.
They eventually found the final monkey and officials revealed three others had to be euthanised, but didn't offer a reason why the animals were put down.
Kristen Nordlund, a spokeswoman for the US Centers for Disease Control and Prevention (CDC), explained that the euthanised monkeys were killed in accordance to American Veterinary Medical Association guidelines.
The other 96 monkeys were fine.
The monkeys were en route to a 'CDC-approved quarantine facility', according to the ABC, after they arrived into New York last week on a flight from Mauritius.
The CDC didn't reveal what the monkeys were being used for, however they're usually tested in laboratories for medical studies or scientific research.
This specific breed of monkey has been used in the past for 'the production of treatments and vaccines for human illnesses', like malaria, herpes and even coronavirus.
The BBC said long-tailed macaques are in high demand at the moment as research teams continue doing studies on Covid-19 vaccines.
Featured Image Credit: Wang Chun / Costfoto/Sipa USA