12:22 PM PT -- The fire appears to have been on the second floor of the structure ... according to the local department, it's been mostly extinguished but crews are checking for anything additional.
The Chappaqua Fire Dept. tells TMZ a structure on the property is ablaze and they are on the scene trying to control it.
The Clinton's bought the home next door to their Chappaqua mansion in 2016 and turned the properties into a single compound.
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