Fire officials believe a homeless person started a blaze Thursday morning that scorched a warehouse behind Master Cleaners in Santa Rosa causing an estimated $450,000 damage.

Regan Masi, vice president of operations at Master Cleaners, said the damage could exceed $1 million, but the business remains open with the main building undamaged.

The warehouse contained cleaning tools and vehicles, and customers’ rugs and furniture. Masi said only a fraction of customers’ property was in the warehouse.

The blaze is considered an act of arson and a homeless person has been identified as being involved, said Assistant Fire Marshal Ian Hardage. The cause of the fire remains under investigation.

Firefighters responded to the call at 1320 Petaluma Hill Road just before 6:30 a.m. Crews had to force their way through doors and walls of the business which had not opened for the day, fire officials said.

The fire was contained by about two dozen firefighters within 30 minutes, Hardage said.

Two homeless individuals sleeping in a tent behind the building along Newhall Bike Path were at the scene at the time of the fire, Hardage said, and their belongings were destroyed.

Masi was aware that homeless people slept behind the warehouse from time to time, but said they had never caused problems before.

“I really appreciate the work the fire and police departments did this morning,” Masi said. “I got a call telling me there was a fire but by the time I got here they had already put it out.”

As of July 31 this year, the Santa Rosa Fire Department had responded to 304 fire incidents. Thirty-five of those — just over 11 percent — were homeless-related incidents, said Battalion Chief Mark Basque.

You can reach Staff Writer Nick Rahaim at 707-521-5203 or nick.rahaim@pressdemocrat.com. On Twitter @nrahaim.