The fire broke out on Mount Serra at around 10:00 pm and has destroyed more than 600 hectares of land, according to Italian media.
Video footage provided by Italian news agency Ansa depicts an orange blaze raging directly behind a street with houses and cars.
Local authorities suspect an arsonist lit the fire.
The President of the Tuscany region, Enrico Rossi, has declared a state of emergency.
Firefighters have been trying to control the blaze since it broke out, but strong winds have made it difficult to extinguish.
Two water-dropping planes are assisting firefighters’ efforts.
“The firefighters were our angels,” said Paola, one of the evacuees who spent the night at a gym in Calci.
“It was an apocalyptic scene and luckily they brought us here to safety.
“I hope this fire was caused by carelessness because I can’t imagine anyone would have such a perverse mind [to start it deliberately].”
The mayor of Calci, Massimiliano Ghimenti, took to Facebook to announce that schools in the area would be closed on Wednesday to give firefighters full access to the area.
Rossi and Ghimenti said evacuees would not be able to return to their homes until Wednesday afternoon.
