(CNN) A fire that spread through a grassy area of Southwest Florida International Airport has destroyed thousands of rental cars, fire department officials said.

The blaze began Friday, spanned 15 acres and originally involved only 20 cars in the grassy rental car overflow area at the airport in Fort Myers, fire department officials said.

But by the time it was extinguished, the flames had destroyed more than 3,500 rental cars, a Lee County Port Authority spokesperson told CNN affiliate WINK

Melinda Avni, Mitigation Specialist for Florida Forestry Service of Caloosahatchee, said authorities were called to put out the fire around 5 p.m. Friday, when there were about 20 vehicles involved.

"By the time we had units on the scene, we had 100 cars (on fire). We lost count after the hundreds," she said.

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