A vacant building in Lake Ronkonkoma that had housed a beverage distributor and gas station was badly damaged by a suspicious fire early Monday morning, officials said.

“There was a large amount of fire and it engulfed the structure in a rapid fashion,” said Nesconset Fire Department Assistant Fire Chief John Martins.

He said the Smithtown fire marshal and the Suffolk County Arson Squad were notified. “We determined the fire was suspicious because of the volume of fire in a vacant structure,” Martins said.

The arson squad is investigating, but the cause is undetermined, according to a police spokeswoman.

The building in the 300 block of Smithtown Boulevard has been home to Lake Ronkonkoma Beverage and a discount gasoline station. It had been vacant for about three weeks after recently changing owners, he said.

The chief said the remnants of the building were declared a hazard and will be demolished immediately.

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The fire broke out shortly before 3 a.m. and was under control by 4:30 a.m., officials said.

Firefighting units from Smithtown, Hauppauge, Ronkonkoma, St. James, Nissequogue, Commack and Lakeland also were at the scene, the chief said.

He said there were no injuries.

With Deborah S. Morris