The investigation involves drones, helicopters and a review of everyone who called 911 about the blazes, he said. "We're going to get to the bottom of what happened," he said, adding that investigators should have an answer to whether there was a "nefarious origin" in the coming days.

Firefighters in New York have knocked down a dwindling brush fire in a wooded stretch of Long Island but officials say high wind gusts could leave the region vulnerable to additional blazes.