A fire destroyed portable toilets and a storage building at Dave Mackie Park early Friday morning but quick work by firefighters saved the baseball grandstands from going up in flames.

Fire District 3 officials said the cause was undetermined.

“It’s very suspicious in nature as to the cause of the fire,” said Deputy Chief Mike Cotton, who was the responding incident officer.

The Island County Sheriff’s Office was notified and is investigating the fire. Sheriff Mark Brown said his department is looking into the cause of the fire because of its suspicious origin and the park’s location in unincorporated Island County.

The blaze spread to the storage unit and former restroom building at the park. “Burning plastic creates a very large, very intense fire when that stuff melts and burns,” Cotton said.

Cotton said the concrete building was deemed unsafe.

An Island County Public Works crew demolished the building Friday afternoon. Steve Marx, assistant public works director, estimated the property damage to be about $10,000.

The old, wooden bleachers at the ballfield were damaged but intact.

About a dozen firefighters from stations 32, 33 and 36 responded and knocked down the fire before it spread to the bleachers. The damage was limited to the siding on the grandstand.

“They’re ready for another baseball game,” Cotton said.

Either three or four portable toilets were destroyed about 2:45 a.m. Fire district officials said the number was difficult to determine because of the destruction. Cotton had yet to hear from the service provider about how many toilets were delivered and the cost of the damage, but he knew they were brought to the park recently.

Firefighters doused the flames quickly and spent about two hours checking for hot spots and flare ups, ensuring the fire didn’t extend to the grandstand.

No one was injured. That doesn’t mean there are no victims, however.

“The victims of the fire, of course, will be Island County Parks,” Brown said.

The portable toilets that were destroyed were improperly delivered to Dave Mackie Park and were intended for use at the Whidbey Island Triathlon, either at Goss Lake or South Whidbey Community Park.

The initial call was reported as a structure and bleacher fire. Cotton and the responding firefighters were relieved to see the blaze limited to the portable toilets and the roof.

“I think what you had is vandalism,” Marx said. “Someone saw something and said, ‘Hey, let’s light something on fire.’ Someone had malicious intent.”

The cost for portables was $3,300. The bulk of the $10,000 property damage value was in labor and materials to build the former restroom building. Marx said the contents of the building were limited.

“We had minimal things in there — lime and some grass seed,” he said.

Brown said there were no witnesses as of Friday afternoon.

Anyone with information is asked to call Island County Sheriff’s Office, at either 360-679-7319 or 321-5113, ext. 7310.