Emergency services were called to the fire at Fife Zoo in Cupar this afternoon shortly after 12pm.
Crews responded as pictures on social media showed smoke filling the skyline.
The fire reportedly started in a soft play building with four fire crews in attendance.
All visitors have been evacuated from the zoo and keepers safely evacuated the marmosets, which were in the enclosure closest to the fire.
One eyewitness told Fife Free Press: “There is smoke and flames pouring out of the soft play building.
“Luckily the keepers were able to evacuate the marmosets safely. Their enclosure was closest to the site of the fire.
“It looked at one point like the firefighters had got the blaze under control, but the flames have now taken hold of the building.
“It’s a devastating blow for the owners, with the facility only in its infancy.”
The zoo reopened on June 29th to visitors after being closed for three months due to COVID-19.
More to follow.