FAIRFIELD — Several people called 911 Monday evening after they were startled by what police said was the use of “flash-bang distraction device” as officers executed a search warrant at a home on Elm Street.

It was necessary for police to use the device because they were conducting a high-risk search and it offered a level of safety for officers, according to Officer Casey Dugas.

Police served the search warrant at about 9:30 p.m. and authorities used a loudspeaker to order that anyone inside exit the home. State troopers then used the device to further prompt anyone to leave.

Dugas on Tuesday declined to specify what the investigation and search warrant were for, but said no one was taken into custody. He did not provide any further details.

Evidence was collected in the search and the investigation is ongoing. There was no risk to the public, Dugas said, and in the interest of officer safety and the element of surprise, officers did not warn neighbors of the noise ahead of time.

Authorities said charges are expected to be filed as the investigation continues. In addition to state police, Fairfield police were assisted by the Somerset County Sheriff’s Office and U.S. Border Patrol.