Johnny Galecki's Ranchland Up in Smoke, First Pic

EXCLUSIVE

‘Big Bang Theory’ star Johnny Galecki‘s burning ranch created a massive cloud of smoke over Santa Margarita, CA — and destroyed his beloved getaway home.

TMZ obtained this photo of the brush fire burning out of control Tuesday. As we first reported … Johnny’s house went up in flames Monday night, and parts of his 300 acres of land were also scorched. No one was hurt. 

His pad sat about a half mile up the road from the entrance to the ranch in San Luis Obispo County.

According to CalFire … they’ve reduced the number of firefighters from 1200 to 600 and the fire is roughly 75% contained.

We’re told 2 other homes burned down in the massive fire. Johnny told us he intends to rebuild.