WINCHESTER — No injuries were reported from a two-alarm fire at a fireworks store in town Monday afternoon. But the merchandise and interior of Stateline Fireworks at 151 Keene Road (Route 10) are a total loss, according to Winchester Fire Chief Barry Kellom.

First responders were called to the scene at around 3:30 p.m., at which point fireworks had already gone off in the part of the building nearest Mechanic Street, he said. The structure’s sprinkler system kept the fire contained to one area of the building, he noted.

But, he said, the damage to the interior was extensive.

“Whatever didn’t end up getting burnt in the fire, the sprinkler system ended up ruining,” he said.

Kellom said the cause of the fire is under investigation. An investigator from the N.H. Fire Marshal’s Office was on the scene Monday evening. Representatives from the Fire Marshal’s Office were not available for comment Tuesday morning.

Stateline is an outlet store that sells fireworks, and its website touts a wide selection of different types and brands.

Kellom said the store is required to have a sprinkler system, and people are prohibited from having an open flame within 300 feet of the building.

Stateline co-owner Michael Dapkus of Portland, Conn., said there were no customers in the store when the fire started, and he and an employee were outside, at the opposite end of the property. He said they first heard fireworks going off, and wondered who was firing them. But when they reached the other side of the property, they saw the side of the building was burning.

The store is equipped with an automatic fire alarm that automatically alerts the fire department if smoke is detected, he said, so they did not call for help. Neighbors had also called the fire department, he added.

Lori Croteau, who lives across the street, said she heard what sounded like a loud rumbling as she was getting ready to make dinner. She initially thought it was a motor vehicle crash, but when she went outside, she saw the flames and called 911.

Dapkus, who has co-owned Stateline for the past decade, estimated the damage to merchandise and the store’s interior at $300,000, and said the property is insured. He said he’s grateful the fire struck in the off-season, lessening the financial blow.

“This would have been a real disaster financially for us if it was around the Fourth of July,” he added.

By around 4:30 p.m. Monday, no flames were visible outside the building, and light smoke that smelled like sulfur and phosphorus emanated from the metal structure. Soot from the fire coated parts of the building and a white truck that had had been parked near the flames.

Firefighters wearing masks and oxygen tanks walked in, out and around the store, removing charred shopping baskets, boxes and other debris. By 5 p.m., the fire was declared under control, according to Southwestern N.H. District Fire Mutual Aid.

As the afternoon progressed, smoke gave way to water. A large puddle carrying a deluge of fireworks began to form in the parking lot. Water from the sprinklers and the fire hoses also leaked from the walls of the building.

Fire departments from Winchester, Keene, Hinsdale, Richmond, Swanzey and Northfield, Mass., were on the scene Monday afternoon, with Winchester police officers diverting traffic. The road re-opened around 9:15 p.m., according to a post on the Winchester Police Department Facebook page. At least nine engines responded to the fire, and more than a dozen firefighters helped contain it.

Dapkus said he intends to begin cleanup as soon as the investigation finishes and the structure is deemed safe to enter, with the goal of reopening the store in January. He said he’s thankful none of the nearby houses were damaged.

“No one got hurt, and you can always replace the fireworks,” he added.