FOX ISLAND, N.Y. (CBSNewYork) -- There's a mystery on Fox Island in Long Island's Great South Bay.
Across Long Island's South Shore communities, the conversation is all about the 4-foot wide, 2-foot deep crater created by an illegal explosion on an undeveloped island off Lindenhurst, accessible only by boat.
"I had just gotten out of the shower and I actually thought something hit the roof, it was so loud," Lindenhurst homeowner James Messina told CBS2's Jennifer McLogan on Monday.
John Sacchitello was woodworking at Venetian Shores Pavilion when he said he was nearly knocked off his feet and saw sand rise in the distance. Fox Island is more than a mile offshore.
"It was just a huge boom. My first instinct was somebody's boat exploded. But the way the smoke dissipated so rapidly, I figured someone set something off," Sacchitello said.
"I had no idea what it was. It's definitely a scary situation because you don't know what it is," Huntington resident Daniel Rivera said.
"Focused on a bunch of pictures that came out of a boat that may have had two, maybe three young people on the boat leaving the scene," Babylon Supervisor Rich Schaffer said.
Suffolk County's Marine Bureau sprang into action.
"Obviously, our department is concerned as to why someone would detonate a device of this size and magnitude on an uninhabited island," Suffolk County Acting Police Commissioner Stuart Cameron said.
A 23-foot vessel with stripes was spotted. Were they possibly duck hunters or fishermen?
"I saw a police boat -- bay constable -- go across the bay and approach a boat," Babylon resident Roger Tursi said. "I hope they catch him because that's not good."
Investigators say it could have been anything from a pipe bomb to dynamite, and are not ruling out that it was a possible trial run for a future criminal act. They are imploring the public for tips.
Editor's note: This story first appeared on Nov. 29.
for more features.