Hudson County emergency officials tested alert sirens Friday in five separate drills and spooked some residents.

"It's a little bit disturbing, you know. I don't know what is this sound. I don't know this alarm," says Morris Murkous, of Jersey City.

The technology is used at nuclear power plants to warn workers there of emergencies, but Hudson County installed 31 stations so it can alert residents of weather-related emergencies and other threats.

Each station consists of eight sirens, which can be heard up to three-quarters of a mile away. Before the sirens, Hudson County didn't have a warning system in place, says Jack Burns, the alarm testing coordinator.

"We really didn't have anything," says Burns. "Some of the municipalities in our county had the reverse 911."

The sirens cost about $800,000, and were tested in Secaucus, North Hudson, West Hudson, Jersey City and Bayonne.