Investigators suspect that an arsonist is to blame for a fire at the 99 Cents Only store on East 10th Street Wednesday night, according to Gilroy firefighter Heinz Maibaum.

“It’s still under investigation as to who started it, but it was a who,” he said.

The preliminary investigation revealed that the suspected arsonist used a lighter from inside the store to ignite a row of plastic flowers displayed outside around 9 p.m., Maibaum said.

The building’s sprinkler system activated, helping to control the blaze while workers doused it with a fire extinguisher, he said.

All three of Giroy’s fire stations responded to the call, but two were sent away after the relatively small fire was brought under control.

The water from the sprinklers caused the most damage, Maibaum said, but the building’s owner said the products inside the inundated boxes were largely unharmed.

“We were there for at least two hours helping them clean up. There was water everywhere,” Maibaum said.

Gilroy police also responded to the incident and are continuing to investigate, said police spokeswoman Amanda Stanford.

The fire followed a small vegetation fire around 3 p.m. that day involving a 30-foot patch of dry grass on the north end of Rancho Hills Drive.

The fire was small by wildland standards, and firefighters, including an engine from the South Santa Clara County Fire Protection District, were able to quickly bring the fire under control, said Maibaum.