Arson is the cause of the 1,100-acre fire that last month set parts of Manorville and Ridge ablaze, destroying at least three homes and forcing evacuations, according to a preliminary state report.
The state Department of Environmental Conservation report, sent last week to the Suffolk County Police Arson squad, said the fire was intentionally set.
The incendiary classification means "someone willfully set the forest on fire in some kind of action," Col. Andrew Jacob, assistant director of New York State Forest Rangers for the DEC said in an interview. The report did not say how the agency arrived at that classification.
Suffolk County police, the lead agency in the probe, said they were still investigating the cause of the April 9 fire. No arrests have been made.
"It doesn't appear the fire was born from natural causes but that doesn't necessarily mean the fire was intentionally started," a police spokesman said. "There may come a time when we make the determination that it was arson, but we're not there yet."
DEC forest rangers are sworn police officers tasked with preventing and putting out wildfires on state land. They also support local fire departments, which can include investigating causes, Jacob said.
Forest rangers categorize fire causes into one of 12 classifications, including arson/incendiary, lightning strikes, debris burning and miscellaneous.
Jacob declined to give specifics about what set the fire.
While the Suffolk County Police Department is the lead agency, the DEC, fire marshals in the towns of Riverhead and Brookhaven, and officials from the Ridge and Manorville fire departments and Brookhaven National Laboratory are involved in the probe, Suffolk police Deputy Inspector Harold Jantzen said earlier this week.
Police investigators are still running down leads and talking to witnesses. They were on the scene even as the command post was operating and firefighters were still battling the flames, he said.
It was the tenth-largest wildfire in recent state history, left three firefighters injured and took days to fully contain.
William Hille was one of three Manorville firefighters hurt when winds picked up and engulfed their brush truck. He was burned on his hands, ears and face, and has two to three weeks left to heal before he can go back to work.
Of the arson designation, he simply said: "It is what it is . . . It could just be a bunch of dumb kids playing with matches in there. They just didn't know better."
Suffolk County Executive Steve Bellone and Brookhaven Town Supervisor Mark Lesko did not respond to requests for comment.
No specific origin point for the fire has been named publicly, but DEC forest rangers and a Brookhaven fire marshal said it began in the vicinity of wooded lands that are part of Brookhaven National Lab, which is federal property.
The day of the fire was considered a red flag day, signifying that fire conditions were high. On red flag days, the lab prohibits burning, cutting or hot work outside the facilities, Mike Bebon, deputy director for operations said earlier in the week.
Lab spokesman Peter Genzer said Wednesday it would be inappropriate to comment on the fire's cause as lab officials had not seen the DEC report.
"Once we have the report, the lab, our legal counsel and the Department of Energy will work together to determine what, if any, special actions need to be taken," Genzer said.
Acres burned: More than 1,100
Firefighting effort: More than 100 fire and rescue units in Suffolk and Nassau County responded.
Buildings destroyed: At least three houses, one commercial building and several other structures, according to latest available figures.
Injuries: Three firefighters suffered burns; all were treated and released.
Lasted: Started April 9, fully involved through April 10, fully contained by the April 12
Winds at the time: Up to 30 mph and more.
Areas affected: Manorville, Ridge, Riverhead and other communities.