Update, March 10, 1:30 p.m.: Suffolk County police arson detectives have preliminary ruled the cause of the brush fires on Saturday to be accidental, the department announced on Monday. "Detectives believe the cause is related to a fire that spread following an attempt to make s'mores at a home on North Cozine Road in Manorville. It’s believed strong winds spurred additional fires from embers, leading to the brush fires."
Update, March 9, 1:40 p.m.: Suffolk County Executive Ed Romaine addressed the public earlier today, putting the total number of acres burned in the Pine Barrens around Westhampton Beach at more than 600. And while all flames are reported to have been extinguished, only about 22 percent of the burn area is at present contained by a perimeter, and work there is ongoing.
The cause is still under investigation, Mr. Romaine said.
Update, March 9, 12:15 p.m.: "I am on site this Sunday morning and am closely monitoring the situation with the Pine Barrens fire," Representative Nick LaLota has reported. "I am in constant communication with local first responders, including the 106th Rescue Wing and other agencies involved in containment efforts, especially FRES [the Suffolk County Department of Fire, Rescue, and Emergency Services] and County Executive Romaine. The coordinated response has been impressive, with over 90 volunteer departments and local police working hard to contain the fire."
"As of now, the fire is still being actively contained, but I don't have an exact percentage on containment yet," Mr. LaLota continued. "The situation is evolving, and the focus remains on ensuring the safety of the community."
"I stand ready to push for federal resources if the situation escalates and meets the threshold for federal assistance."
Update March 8, 10 p.m.: A massive, wind-whipped brush fire that started in the Pine Barrens area of Westhampton Beach around 1 p.m. today and shut down Sunrise Highway in both directions has reportedly been mostly contained as of tonight.
Volunteers from the East Hampton Fire Department — one of many that responded from across the East End and as far east as Montauk — had been released from duty by about 7. (But, no rest for the weary, they were immediately called to another, far smaller brush fire near houses on Montauk Boulevard off Route 114 in East Hampton.)
The Westhampton wildfire prompted Southampton Town Supervisor Maria Moore to declare a townwide state of emergency, effective at 3 p.m. "Dry weather and high winds, along with damage to woodland areas caused by Southern Pine Beetle infestation, is exacerbating the conditions for dangerous wildfires," she said in a release.
Given its proximity to the fire, the 106th Rescue Wing of the Air National Guard at Gabreski Airport in Westhampton Beach evacuated personnel from the base and deployed "two base fire trucks" and an "HH-60W Jolly Green II helicopter" to combat the blaze, according to a release from the base.
Originally, March 8: 4 p.m.: Sunrise Highway is closed east of Exit 62, as firefighters from across the East End battle major brush fires in the area, Southampton Town police said in an alert. Smoke from the fires could be seen as far away as Connecticut and from East Hampton.
“Minutes ago, I spoke with County Executive Ed Romaine about the brush fire in the Pine Barrens and informed him that the State of New York is here to provide any resources and support he needs," Gov. Kathy Hochul said in an emailed statement on Saturday afternoon. "The New York National Guard has already begun providing air support by helicopter and is coordinating with local law enforcement. I have also deployed personnel from the Office of Emergency Management, Office of Fire Prevention and Control, Department of Transportation, Department of Environmental Conservation, State Parks, and the New York State Police to assist Suffolk County’s response to this crisis."

A number of South Fork departments are assisting in the effort to bring the fires under control on a day when wind gusts are forecast to reach over 40 miles per hour.

Shortly before 2:30 p.m. Southampton police said Speonk-Riverhead Road was also closed and asked people to "stay clear of the areas."
The Amagansett Fire Department was among those on scene, its chief, Chris Beckert, confirmed, as was the East Hampton department, Chief Duane Forrester said, adding to what he called "a busy few days for us. We were in North Sea last night till about 1 a.m. or so," followed by a training exercise this morning. "We went right into a working structure fire after that on Park Street" in East Hampton, before going to assist with the Westhampton Beach blaze.

Montauk firefighters had already headed west at that point, Marcos Baladron, the East Hampton Village administrator, said, adding that the area affected was extensive, maybe 50 acres. The fire's proximity to the road could be a blessing, he said, if it acts as a fire break.
By around 5 p.m. the rising smoke was visible from Exit 65 on the Long Island Expressway.
This story will be updated as more information becomes available.
With Reporting by Christopher Gangemi