(AP) - New Jersey officials say a coding problem mistakenly caused a test emergency alert about trouble at a nuclear plant to be sent out publicly.

The message was part of a scheduled training exercise staged Tuesday night at the Hope Creek plant in Salem County.

State police say the message - created to test an electronic communications system - was only meant for a small group of people participating in the exercise. But it instead was sent publicly, causing many residents to believe a real emergency was taking place.

Officials moved quickly to inform the public about the error.

But an official in neighboring Cumberland County says their 911 Communications Center was inundated with thousands of calls regarding the warning.

State police say the coding error has been identified and corrected.