FREELAND, Wash. -- The first fire ignited a trash can.

One of the latest: a house.

Now, after at least seven fires in recent weeks, the search is on for a firebug on Whidbey Island.

The Island County Sheriff's Department is trying to determine if there's a serial arsonist on the prowl.

"We want the public to keep their eyes open," said Detective Ed Wallis.

One of the biggest fires so far was at Angus MacDonald's home.

The small house, located right off the main highway on Whidbey Island, became a fireball in the middle of the night.

It was being renovated into office space, with the new tenants set to move in.

"Yeah you're sad and it's devastating," MacDonald said. "Then you get mad. Then the anger hits, and you're upset with whoever's doing shenanigans."

He estimates he has spent about $100,000 in repairs.

"Something can go further if this guy keeps horsing around and they don't find him," MacDonald said. "Cause he started out small and he keeps working bigger."

Just up the road from MacDonald's, the old Freeland Hall nearly went up in flames.

New wood has already replaced the charred damage.

Along Admiralty Inlet -- with expensive homes and million dollar views -- a public restroom was ignited.

All around South Whidbey, police say dumpsters and garbage cans and seemingly anything else can become a target.

Wallis warns the public to be cautious.

"Report suspicious activity, especially at night," he said. "Make sure they're not leaving gas cans out or combustibles stacked up around buildings where they could be an easy target."

So far, investigators say there are no suspects.

But the fires appear to start outside, and they all have been happening late at night, between 1 and 3 in the morning.

Several agencies from nearby counties are helping the Island County Sheriff's Department investigate.