The Suffolk County Police Department said the explosion occurred on Fox Island, off the coast of West Babylon, around 11:40 a.m. when a device was detonated. Authorities received nearly three dozen 911 calls, the department told Fox News.
No injuries were reported. Fox News has reached out to the FBI.
Investigators are not ruling out the idea that the incident may have been a test run for something bigger, such as a possible terrorist attack.
“Terrorism is always a concern because people do test devices before using them,” a police spokeswoman told Fox News. “The SCPD is investigating with the FBI Joint Terrorism Task Force on this investigation.”
The blast left a crater on the north side of the island that measured 4 feet wide and 2 feet deep. Authorities are seeking a boat seeing leaving from the area at the time.
It was described as 23 feet long with stripes.
Investigators have ruled out a sonic boom by an aircraft.