PINOLE -- An intense one-alarm fire left two homes directly behind Pinole Valley High School with more than $25,000 in damages each, a fire inspector said.

Crews responded to the blaze shortly before 5 p.m. on the 2000 block of Sarah Court. When they arrived, firefighters found the upper sections of two neighboring homes on fire, said Contra Costa Fire Protection District Battalion Chief George Laing.

Though the cause of the fire is still under investigation, Laing said it appears something caused a spark that ignited a shed containing aerosols. The fire then caught some debris and a fence on fire and subsequently caused a gas meter to fail, releasing gas into the air and fueling the blaze.

The aerosol cans as well as a propane tank in the space between the two homes became so hot they burst, Laing added, and then the fire spread into the homes' attics.

The explosions could be heard at the school, Laing said, where students were on the baseball field.

Laing credited firefighters for their quick work on the "very intense" blaze, saying they were able to contain it in roughly a half-hour.

No injuries were reported, and crews were still working to determine if the homes were inhabitable Thursday night.

Laing said each home suffered between $25,000 to $30,000 in damages, and the cost will most likely rise as both homes also suffered water damage.

Contact Katie Nelson at 925-945-4782 or follow her at Twitter.com/katienelson210.