Three people, including two minors, were arrested after "ghost guns" and a 3D printer were recovered from an unlocked room at a state-licensed day care facility, New York City officials announced Wednesday.

The arrests were related to a "long term" investigation into the manufacture and sale of ghost guns, also known as privately made firearms, according to Rebecca Weiner, the New York City Police Department's deputy commissioner of intelligence and counterterrorism bureau. Police said they found multiple 3D-printed firearms at a private residence in East Harlem.

Karon Coley, 18, was arrested for his involvement in 3D-printing the firearms at his mother's home, which police said was operating as a licensed day care center. Coley faces charges of illegal firearms possession, manufacturing of an assault weapon and reckless endangerment, Manhattan District Attorney Alvin Bragg said at a news conference Wednesday.

Officials did not release the names of the minors who were also arrested. Their relationship with Coley is not immediately known.

The arrests comes nearly two weeks after the death of a 1-year-old boy who was exposed to fentanyl at a Bronx day care center along with three other children. New York City officials vowed to protect children in the city on Wednesday and Mayor Eric Adams proclaimed city officials will "lead the entire country" in safety at day care facilities.

"This is a heartbreaking scenario of thinking that you're dropping your child off to a place of safe haven just to find out that it was a dangerous environment," Adams said at the news conference. "We're going to work united. We are clear that we must protect children in this city."

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'He's not making little robotic toys, he's making guns'

The investigation revealed that a group of individuals, including some minors, were purchasing ghost gun parts and materials to print 3D firearm components from online retailers, Weiner said. Some of the purchases were also fraudulently obtained, including with alleged identify theft of multiple individuals across the country.

Investigators found a 3D printer and printing tools, and two completed 3D-printed guns and an assault pistol that was in the final stages of assembly inside an unlocked room at the East Harlem day care facility. Police arrested three people, including two minors and Coley, who was taken into custody at the day care site.

"You've got an 18-year-old in his room, 3D printer. He's not making little robotic toys, he's making guns," Adams said. "That should be scary to everyone."

According to Christina Chang, executive deputy commissioner and chief program officer with the Department of Health and Mental Hygiene, the day care was being operated by Coley's mother inside her private residence. The initial license for the day care was issued in February 2021 and it was last inspected in February this year, Chang said.

Health inspectors had found three violations related to documentation around feeding and sleeping schedules; preferences from families; and verification from doctors that children did not have any infectious diseases, Chang added. The day care was cited for those violations but Chang said the facility "took corrective action and verified that the paperwork was done."

What are ghost guns?

Ghost guns, or private made firearms, are homemade guns that are often assembled from 3D-printing or kits purchased online. The firearms can be purchased without background checks and do not have serial numbers, making them untraceable.

In a landmark report published in February, the Bureau of Alcohol, Tobacco, Firearms and Explosives found that the number of suspected ghost guns recovered by law enforcement and submitted to the bureau for tracing increased by more than 1,000% between 2017 and 2021. And the number more than doubled from 2020 to 2021.

Law enforcement agencies across the country recovered and traced nearly 38,000 suspectedghost guns between 2017 and 2021.

Weiner noted that ghost gun operations are a "growing trend" in New York City. In 2021, the NYPD recovered more than 260 ghost guns and the number almost doubled last year with over 430 recoveries.

"Ghost guns and 3D printed firearms operate just like commercial firearms," Weiner said. "In the hands of teenagers, they can inflict just as much violence."

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Bronx day care fentanyl poisoning

On Sept. 15, NYPD officers found three children unconscious and showing symptoms of a toxic opioid exposure, according to court records.

An 8-month-old girl and two boys, 1 and 2, were administered the overdose-reversing drug Narcan but only two of the children recovered. One-year-old Nicholas Feliz Dominici died from suspected fentanyl poisoning.

Another 2-year-old boy from the day care was later admitted into a hospital when his mother noticed he was "lethargic and unresponsive." He was able to recover after being administered Narcan.

Investigators found a brick of fentanyl on top of playmats for the children and equipment often used to package drugs in other areas of the day care site. A further search revealed a trap door in a play area, which contained more drugs.

Four people have been arrested and charged in connection to Dominici's death, including Grei Mendez, 36; Carlisto Acevedo Brito, 41; Renny Antonio Parra Paredes, 38; and Felix Herrera Garcia, 34.

Mendez, who operated the day care center, and Acevedo Brito, who had been living in the same building, were charged in state court with murder. Paredes was charged with narcotics distribution resulting in death and Herrera Garcia was charged with conspiracy to distribute narcotics resulting in death.

Contributing: Grace Hauck, USA TODAY; The Associated Press