A possible arson brought commotion to a quiet Coupeville street on Monday.

While firefighters were able to contain a house fire, a second fire destroyed a smaller structure. Nobody was injured.

Police responded first to reports of a residential fire at a Northeast Third Street address. Central Whidbey Island Fire and Rescue came next, tending to flames rising from the lower floor of the main house.

The crew put it out quickly, said Fire Chief Jerry Helm. The fire stayed inside the bathroom. While a towel and towel bar received some damage, the structure persisted.

As the crew began searching for any remaining fire after the large flames were extinguished, a large black thermal column rose from a separate, 15-by-20-foot storage shed. Within the hour, the second fire was contained, but the shed was lost completely.

Helm said there was a person walking away from this fire who was seen by the conflagration of both structures. Law enforcement immediately arrested him under suspicion of arson.

Sheriff Rick Felici said that the suspect, a 52-year-old man, is “severely mentally ill.” While he did start the fires, he will undergo an involuntary mental health evaluation. Police are still investigating to determine if they should press charges.

The property owners waited outside the home with dogs in a pickup truck. They declined to comment.