LACONIA — An arsonist is to blame for a Memorial Day fire that destroyed a historic brick storage building at Paugus Bay Marina in Lakeport.

Laconia Fire Chief Kenneth Erickson said firefighters were just cleaning up a brush fire a mile away along the Winnipesaukee-Opechee-Winnisquam recreation trail after 2 p.m. when Lt. Lisa Baldini looked up across the water and saw smoke.

“They were responding before it even toned out,” Erickson said.

Officials at the Laconia Police Department have a “person of interest” spotted at both fire locations, Erickson said.

The second blaze appeared to have begun in the brush behind a century-old 50-by-30-foot storage building, which is within 50 feet of Paugus Bay. It contained Styrofoam and barrels of oil and was “built like a fortress,” the chief said. It had a rotating floor on which steam locomotives would be brought in and turned around, Erickson said.

He said firefighters worked quickly to protect a huge boat storage building with about 160 vessels stacked only 30 feet from the fire.

He said occupants of more than 200 boats in the bay watched the two-alarm fire at its height; the smoke column went over 500 feet in the air. The fire brought 34 firefighters from surrounding towns and was declared under control about 4 p.m.

Marina owner Kevin Keenan has said the building will be taken down within the week.

It was at least a $100,000 loss, Erickson said.