Great balls of fire ... a 61-year-old man tried to fend off cops serving an eviction notice by attacking them with an improvised flamethrower ... and the fireball is on video!!!

Body cam footage shows the moment cops bust into Darron Dunn's Oklahoma apartment, and he greets them with a flaming ball of fire.

According to the incident report, obtained by TMZ, the Oklahoma County Sheriff says Dunn pointed and sprayed an aerosol can at deputies and ignited the chemicals with a lighter ... and boom! Homemade flamethrower.

When the flames died down, the OCSO says someone spotted what they believed to be a makeshift explosive device -- a car battery hooked up to wires that went through the living room to a device near the front door.

The officers hightailed it outta there and called in the bomb squad and tactical team, who defused the situation and disabled the homemade device.

Dunn was brought to a nearby veterans hospital to get some medical issues checked out ... and was arrested.

According to the incident report, he's facing a felony assault and battery charge, a felony explosives charge, and a misdemeanor for obstructing an officer.