FRANKLIN – The landmark Franklin Trading Post on Route 182 was destroyed by fire overnight Wednesday in what witnesses say was a spectacular blaze caused by a bolt of lightning at about 10 p.m.

A State Fire Marshal was expected at the scene sometime Thursday, according to Fire Chief Robert Grindle, who would not speculate on the cause pending an investigation.

But Grindle admitted it seems probable that lightning from one of the worst electrical storms in history started the fire, which took almost six hours to contain fully.

The ruins of the popular store and restaurant were still smoldering at noon Thursday.

“This place was the heartbeat of the town. What a slap in the face,” said resident Eddy Jordan, who joined scores of people Thursday who stopped to see the ruins and offer their regrets to the owners.

Tim Benson, who owned the trading post with his wife, Katrina, said the couple lost $300,000 to $400,000 in property and inventory. The Dedham couple had insurance on their store.

“We hope to rebuild, but that will depend on the insurance company,” Tim Benson said as he sat against a gas pump early Thursday afternoon.

The fire chief’s wife, Becky, wiped tears from her face as she glanced at the blackened ruins where she has worked as a cook, clerk and waitress for 13 years. She also is a volunteer firefighter who helped douse the fire through the night.

“There are a lot of memories,” she said of the trading post, which has been a fixture on the main road since 1976. The Bensons have owned the store for two years.

“This would have been our third summer,” Tim Benson said.

The Bensons had their store fully stocked, plus some: They had bought extra provisions for the long July Fourth holiday.

An island of gas pumps was not seriously damaged, but they gave the firefighters cause to worry, according to Chief Grindle. He pointed to the tall platform over the island where the plastic was melted. A plastic trashcan between the gas pumps also was badly melted.

The Grindles said Bangor Hydro-Electric took 90 minutes to respond to their call to cut the power, which presented another danger to firefighters trying to drown a fire with water while working around live electrical wires. The gas pumps also were still “live,” and the fire chief was worried that the fire would ignite gas fumes from the nearby island.

“This should have been a priority call,” he said, shaking his head.

Grindle said he notified Bangor Hydro twice about the seriousness of the fire and his concerns about the live wires and the gas pumps.

Bangor Hydro could not be reached for comment Thursday because of the July Fourth holiday.

Corey Chandler, 16, lives next door to the trading post. Ten minutes after he and his friend, Jonathan Kidder of Ellsworth, also 16, walked over to the closed store and bought sodas out of a machine, they heard a sound they thought was a bomb.

They instinctively fell to the floor. Chandler said he was so scared he cried. It was 10 p.m.

“It was a big, huge boom,” Chandler said. “I thought it was a bomb.”

Kidder added, “The hair stood up on my arms and my body tingled.”

Fifteen minutes after the boys heard the boom, another friend called them to say she heard the trading post was on fire. Chandler and Kidder went to the window and saw the store in flames.

They left Chandler’s home immediately, but returned at about 11:30 p.m. to watch the firefighters battle the roaring blaze.

“I grew up in this store,” Chandler said. He said he got his first “real job” from the Bensons, who hired him to stock shelves and help around the store.

The Grindles said an Ellsworth firefighter who lives in the Hancock-Franklin area also heard the crash and later told the couple that he knew the lightning had found a target.

Grindle said 20 volunteer firefighters converged on the scene shortly after the call went out at 10:20 p.m. While crews from Hancock, Franklin and Eastbrook fought the fire, aided by seven trucks, volunteer departments in Waltham, Lamoine and Sullivan covered the entire six-town region.

Grindle said the firefighters worked tirelessly to drown the blaze, staying on site until 3:30 a.m. His crew stayed until later in the morning and a truck was still spraying the ruins more than 12 hours after the fire started.