Schoolchildren in the vicinity are being allowed to leave schools to go home, according to local broadcaster WCAU.
The road leading to the town of Paulsboro has been reopened but a limited evacuation is still in force.
The Coast Guard told WCAU that there is no immediate threat.
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It comes after security was stepped up around the country following the Manchester Arena attack which killed 22 people.
A murderer nicknamed 'Houdini' after escaping the death penalty seven times has been given the lethal injection.
The distress signal sparked a police hunt in the area to find the person or group who made it.