Gov. Kathy Hochul declared a state of emergency a day earlier after four separate fires broke out across large swaths of Long Island’s Pine Barrens region, prompting closures to the highway and evacuations of a military base.

As of Sunday, all visible flames had been knocked down, including the last remaining fire burning in the hamlet of Westhampton, according to Suffolk County Fire Coordinator Rudy Sunderman. He said at a Sunday news conference that crews were working on containment lines around the fire to prevent further spread. Authorities said the fire had not grown since early Sunday.

Still, officials were cautious as wind gusts of up to 30 mph (48 kph) were expected Sunday, according to the National Weather Service,

“We’re concerned because the winds are still blowing, that might spark up again,” said Suffolk County Executive Ed Romaine.

Romaine thanked firefighters who worked through the night, adding that more than 80 volunteer fire departments battled the blaze, which burned about 600 acres (243 hectares).

Two firefighters were hospitalized for injuries and released, according to Sunderman.

The cause of the fire remained under investigation.

Dozens of detectives were interviewing 911 callers and using drones. Suffolk County officials said earlier that the police department’s arson squad had initiated an investigation into the blaze, though there was no immediate evidence to suggest arson.

“We’re going to get to the bottom of what happened,” said Suffolk County Police Commissioner Kevin Catalina. “At this time it’s too early to tell whether or not this fire started naturally or there’s some nefarious origin.”

At least two commercial structures were damaged.

Roughly 15 miles (24 kilometers) west, officials were monitoring a small brush fire along Sunrise Highway early Sunday, Brookhaven Town Supervisor Daniel J. Panico said. But there were no visible flames as of Sunday morning.