LOS ANGELES — The Los Angeles County Sheriff’s Department is adding a drone to its arsenal.

Sheriff Jim McDonnell says Thursday the unmanned aircraft, marked with the word “RESCUE” on both sides, will only be used in limited circumstances to assist deputies with rescues, bomb scares, arson investigations and tactical situations.

Authorities say the tool is a valuable asset to evaluate potential threats during standoffs and active shooter situations. The $10,000 aircraft can fly up to 400 feet for about 20 minutes on a single charge.

Activists have raised privacy concerns about law enforcement agencies using drones. But McDonnell vowed the technology “will not be used to spy on the public.”

In 2006, the sheriff’s department demonstrated a drone to the media, but the aircraft crashed into the ground.