NEW YORK — One private drone crash-landed in midtown Manhattan. Another caused alarm by hovering over Times Square amid tight security during Super Bowl week. Most recently, authorities say, another had a close brush with a police helicopter near the George Washington Bridge.

Even though it’s illegal to fly the devices just about anywhere in New York City without permission, the incidents and breathtaking videos of Manhattan’s steel-and-glass canyons and sweeping skyline photos suggest that the restrictions are being widely flouted.

Police are concerned that the increasing popularity of drones in such a tightly packed metropolis could carry significant risks, even becoming a potential tool for terrorists to conduct surveillance or carry out attacks.

“So far, we haven’t seen anything sinister with this,” said John Miller, the NYPD’s deputy commissioner of counterterrorism. But “people with enough money and time on their hands are going to buy them and see what they can do with them.”

Drone buffs say the futuristic doomsday scenarios are far-fetched.

“A motor vehicle or a bicycle could just as easily be used to do something nefarious,” said Steve Cohen, a professional photographer who owns a small fleet of drones and organizes meetings for enthusiasts.

The debate comes amid a boom in purchases of what are essentially flying cameras.

Sales appeared brisk Wednesday at B&H Photo Video in midtown Manhattan, where models include palm-size mini-helicopters that sell for less than $100, four-rotor models selling for about $1,300 and eight-bladed “octocopters” that go for more than $6,000. All can be equipped with high-definition video cameras, and some models allow the pilots to see the footage live from the ground.

B&H wouldn’t talk about its sales figures, but salesman Fred Hoffman “guesstimates” that about one in 10 people who come in to his consumer video department are looking for drone cameras.

“We expand to keep adding displays and models,” he said.

Federal Aviation Administration rules permit people to fly unmanned aircraft for recreation at altitudes up to 400 feet as long as pilots keep their aircraft within sight. The agency is working on regulations regarding commercial flights, which are generally banned under current rules.

A New York City man learned last year that pilots also must get official clearance to fly within five miles of an airport or anywhere in New York City airspace, unless taking off and landing in designated “flying fields” in city parks.

The FAA fined the man $2,200 for flying a quadcopter off a Manhattan building in a “careless and reckless manner.” The drone glanced off two other buildings before crashing just south of Grand Central terminal near a pedestrian.

In January, police were alerted to a low-flying drone over the Super Bowl street fair. It was traced to a fashion firm that was using it to shoot a commercial.

The most serious encounter came Monday, when a crew member of an NYPD helicopter on patrol at 2,000 feet spotted a flying object headed in its direction. According to police, the chopper had to change course to avoid a collision.

The helicopter followed the drone until the crew saw it land on top of a van on a street corner, where its owner and another man with a second drone were arrested on charges of reckless endangerment. Their lawyer denied the drones could reach that altitude and compared his clients’ behavior to flying a kite.

In Chicago, where there’s no ordinance regulating drone use, Alderman Scott Waguespack is seeking restrictions to protect personal privacy. He has proposed an ordinance restricting public and private use.

“When I was a kid, we used to have little rockets. Now you have the capabilities to do what the police can do: watch people or watch events,” Waguespack said. “It leaves the door open to people doing whatever they like.”

The growing popularity of drones worries him from a safety standpoint, too.

“If you get 100 of them out there, what if they start hitting each other?” he said.