When a parking garage collapsed in Lower Manhattan last week, killing one person and injuring five others, the Fire Department deployed a “digidog”: a four-legged robot with a Dalmatian’s spotted torso that scoured rubble in a structure deemed too dangerous for humans.

It was, according to its maker, the first U.S. use for the robot in such real-world circumstances.

On the day of the collapse, Mayor Eric Adams hailed the digidog, which was dispatched with several drones to hunt for victims and bodies, saying it had enabled the search operation to proceed safely. On Tuesday, he cited its performance again, reiterating his commitment to using futuristic gadgets for public safety, despite critics’ concerns.

“Some people call them toys,” Mr. Adams said at a news conference. “This is not playtime. This is real time. And this is an administration that is not going to be fearful of using everything possible to save the lives of New Yorkers and to save the lives of first responders.”

The news conference, where Mr. Adams was joined by Laura Kavanagh, the fire commissioner, and other officials, was the second this month where he touted the benefits of such devices while playing down potentially sinister implications.

On April 11, Mr. Adams introduced several new high-tech tools he said the Police Department would soon be using: two security robots; a gun-shaped device that police officers can use to shoot GPS-enabled trackers onto fleeing cars; and two robotic dogs.

The announcement that the police were acquiring the robotic dogs, at a combined cost of $750,000, was a policy reversal. The department had leased one of the devices under Mr. Adams’s predecessor, Bill de Blasio, but abandoned it amid an outcry about its deployment in public housing complexes and its potential for invading individuals’ privacy and being used as a weapon.

“Digidog is out of the pound,” the mayor, who has a longstanding interest in promoting policing technologies and devices, said then. On Tuesday, he insisted that questions about whether the devices might be used against New Yorkers rather than on their behalf were unwarranted.

“These technologies are not going to be intrusive,” the mayor said. “I want to be clear on that.”

But neither Mr. Adams’s assurances nor the robotic dog’s performance in the search operation persuaded critics to join his full-bodied embrace of technology’s public safety role.

“While deploying a robot is, of course, appropriate in situations like this, that doesn’t eliminate the need for transparency about this and other technologies that may have the capacity to engage in massive surveillance and routinely collect massive amounts of private personal data on millions of New Yorkers,” Donna Lieberman, the executive director of the New York Civil Liberties Union, said.

Albert Fox Cahn, a lawyer and the executive director of the Surveillance Technology Oversight Project, agreed that the Fire Department might have sound lifesaving purposes for such robots. But he said that did not make them appropriate tools for the police. Mr. Adams, he added, appeared to be using one application to justify the other.

Mr. Cahn also said officials had not presented enough detailed information about what the device did in the garage’s rubble to establish that it was worthwhile.

“I want to believe that these robots would be effective in a building collapse,” he said. “But we need more than a couple of soundbites.”

Mr. Adams and Ms. Kavanagh said on Tuesday the device had used its thermal camera to determine that no one beyond the six people known to be injured or dead was trapped in the debris, and also to inspect the building’s structural components.

Although the device provides streaming video of what it sees, city officials and a spokeswoman for the manufacturer, Boston Dynamics, said the footage is not recorded, meaning there is no video chronicle of its activities that day.

The Fire Department paid $75,000 apiece for the base model of the two robotic dogs it acquired last year. Several features have been added since, bringing the cost of each to around $250,000, a spokeswoman said.

The manufacturer calls the device Spot, but the Fire Department has named the one on display Tuesday Bergh, after Henry Bergh, the founder of the American Society for the Prevention of Cruelty to Animals.

A video snippet of the device in action at the collapse circulated online shortly after it went to work. The 21-second cut shows the robot toppling onto its side soon after approaching a rubble pile. “That didn’t go so well for the dog,” a voice says.

The device’s primary purpose is to respond to incidents involving hazardous materials, according to Ms. Kavanagh. It is also designed to right itself if it loses its footing, as a video provided by Boston Dynamics shows.

Perhaps seeking to counter any narrative that the robot dog had rolled over and not gotten up, Mr. Adams and other officials went to some lengths on Tuesday to push it onto its side to show that it could indeed stand again.

“All right,” the mayor said when it did.

Emma G. Fitzsimmons contributed reporting.