The cause of the 12-alarm fire that destroyed two structures in downtown Sag Harbor last month will likely never be determined because those buildings were razed and power in the area was shut off before an investigation could get underway, an East Hampton Town official said Monday.

Fire Marshal Tom Baker said in an interview that the Dec. 16 fire, which damaged seven businesses and four apartments — but resulted in no injuries — broke out in one of the two buildings that received the most damage and were torn down. He added that razing the buildings removed evidence investigators needed to determine exactly what happened.

Baker said Suffolk County Arson Squad officials ruled out criminality immediately after the fire “because there was no evidence of that,” but he said that tearing down the Sag Harbor Cinema, a Main Street landmark, and the Compass real estate building three days later hindered the investigation.

Baker added that his decision to have PSEG Long Island cut power in the area over concerns for the safety of hundreds of firefighters who responded to the blaze also meant that an investigation into any possible electrical cause for the fire could not be undertaken. He said that once the power was cut off, the voltage at the time of the fire could not be recreated.

“It’ll be undetermined,” Baker said, referring to how he plans to list the cause of the fire in the report he expects to complete this week. “They’ve removed the buildings so there’s not much more we can look at.”

Baker added that the decision to raze the buildings was made by Sag Harbor Mayor Sandra Schroeder and building inspector Tom Preiato.

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Preiato said in an interview Monday that he stands by that call because the buildings needed to be taken down for health and safety reasons. Schroeder could not immediately be reached for comment.

“They needed to be removed,” Preiato said. “They were touching adjoining buildings and there was the risk of having them fall on them. They weren’t safeguarded at night and there could be vandals — a whole lot of things. . . . And it was not a healthy situation, toxic-wise. We had some oil spill that had to be cleared.”

Preiato added that the two structures had “suffered such severe fire damage” that he, the mayor and Suffolk County engineers all agreed they needed to be taken down, although ultimately it was his decision.

“We would have loved to have learned the cause so that going forward we could prevent something like this,” Preiato said, but the safety of people was more important. “If the cause of the fire has to be undetermined, so be it. Without a doubt, I wouldn’t do it differently.”

Baker said he also stands by his decision to cut the electrical power while firefighters battled the blaze.

“There were 300 firefighters, and it was in their best interest to keep them safe,” Baker said.

Baker said he is expecting an engineer’s report Tuesday on whether another building, the former Brown Harris Stevens real estate offices, should be razed.