A 1-year-old boy died and three other children were hospitalized after apparently "coming into contact with an opioid" at a home-based child care site in the Bronx on Friday, New York City police said.

The boy who died was identified by authorities as Nicholas Dominici.

One of the three children hospitalized is in critical condition, authorities said at a press conference early Saturday.

Police said they received a 911 call from a daycare center reporting three unconscious children just before 3 p.m. on Friday. When police responded, they found two boys, 1 and 2 years old, and an 8-month-old girl, all unconscious, according to the NYPD.

Investigators revealed the children appear to have been exposed to the unknown opioids over an extended period Friday.

A 2-year-old boy who went home at around 12:15 p.m. was later found by his mother to be "acting lethargic and unresponsive," police said. The mother rushed him to the hospital, where the opioid-reversal medication Narcan saved his life.

The children who stayed at the day care ate something at around 1 p.m. and took a nap. When workers went to wake them up at 2:30 p.m., three were unconscious, according to police.

"All three children were unresponsive and demonstrating symptoms of opioid exposure. Narcan was administered to all three of these children in an attempt to save their lives," NYPD Chief of Detectives Joseph Kenny said.

The children who were hospitalized all live nearby in the Bronx. None are related.

The NYPD said they executed a search warrant at Divino Nino Daycare and discovered a kilo press - an item commonly used by drug dealers when packaging large quantities of drugs.

ABC News could not immediately reach the daycare for comment.

"This crisis is real, and is a real wake-up call for individuals who have opioids or fentanyl in their homes," New York Mayor Eric Adams said at a press conference. "Our hearts break for these families that are involved."

The daycare, for children between 6 weeks and 12 years old, recently opened in January and just passed a surprise visit from city inspectors last week with no violations found, according to police.

Two people -- the woman running the daycare at the time of the tragedy and an unidentified man -- are being questioned by detectives, with charges expected, police said.

The city medical examiner will conduct an autopsy to determine Dominici's cause of death, and doctors will take urine and blood from the surviving children to try to figure out what drugs they were exposed to, police said.

"The mere contact is deadly for an adult and it's extremely deadly for a child," Adams said.

NYPD officials said this is an active criminal investigation.

"We should not be here. These children do not deserve this, so please pray for them and their families," NYPD Commissioner Edward Caban said at a press conference.