PERRIS (CBSLA.com) — A third-alarm fire destroyed two acres of pallets at a pallet yard in Perris Friday. It is the latest in a string of pallet fires in Inland Empire. Investigators are now trying to determine if they are connected.

The blaze was reported shortly before 3 a.m. near North Webster Avenue and West Ramona Expressway.

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Miguel Penaloza still doesn’t know what to think about the fire that damaged more than 80 percent of his pallet yard.

He said he’s grateful that the fire started early in the morning, when no employees were around.

“Nothing happened to anyone. It was just material stuff,” Penaloza said. “I really don’t have any words. I was just shocked to find out that it happened to us.”

The propane within the compound set off some explosions, but there was no threat to nearby buildings, according to April Newman of the Riverside County Fire Department.

It took about 45 firefighters three and a half hours to put out the flames.

Southern California Edison crews were also on scene to repair two burned power poles.

The cause of the fire remains under investigation.

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This is the latest in a string of recent pallet fires in the Inland Empire, including one in Ontario last month and another in San Bernardino two weeks ago, which was suspected to be arson.

“The investigators from all the agencies that have had these types of fires within the last few weeks are now coordinating efforts and sharing information,” Cal Fire Battalion Chief Richard Owens said.

Edgar Montes said he has been trying to warn investigators and other pallet company owners since an arsonist targeted his yard in Fontana in January.

His security cameras captured someone lighting a molotov cocktail and throwing it over his back fence. He suspected that whoever did that may be responsible for these latest fires too.

“We have reason to believe that this is terrorist activity. The person or people involved are terrorizing the pallet industry and pallet companies,” Montes said.

He has upgraded his security system and lighting since the fire and advised other pallet business owners to do the same.

Pennloza wished he had taken that advice earlier. “I didn’t think it would happen to us that quick. We were talking about it between our family, but we didn’t really take action.”

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The victims believed the pallet fires were connected and were offering a $32,000 reward that would lead to the arrest of the arsonist or arsonists.