Those attending outdoor parties or barbecues in New York City this weekend may find an uninvited guest looming over their festivities: a police drone.

The New York City police department plans to pilot the unmanned aircrafts in response to complaints about large gatherings, including private events, over Labor Day weekend, officials announced Thursday.

“If a caller states there’s a large crowd, a large party in a backyard, we’re going to be utilizing our assets to go up and go check on the party,” Kaz Daughtry, the assistant NYPD Commissioner, said at a press conference.

The plan drew immediate backlash from privacy and civil liberties advocates, raising questions about whether such drone use violated existing laws for police surveillance.

“It’s a troubling announcement and it flies in the face of the POST Act,” said Daniel Schwarz, a privacy and technology strategist at the New York Civil Liberties Union, referring to a 2020 city law that requires the NYPD to disclose its surveillance tactics. “Deploying drones in this way is a sci-fi inspired scenario.”