The owner of the Bronx daycare center where a 1-year-old died and at least three other children were sickened after coming into contact with suspected fentanyl may have been subletting a room in the tiny facility to a stranger, a source told The Post Saturday, as heartbreaking details about the toddler’s last breaths emerged.

The shocking revelation emerged as a joint task force comprised of members of the NYPD and the US Drug Enforcement Administration are probing the deadly incident.

Meanwhile, the NYPD was interviewing Divino Nino Day Care owner Grei Mendez at the 52nd Precinct Saturday, and is seeking to talk with the man she apparently rented a room to inside the small Morris Avenue facility, sources said.

A kilo press, a device typically used to combine fentanyl with either cocaine or heroin, was found inside the space used by the daycare, officials said.

“This is an item that is commonly used by drug dealers when packaging large quantities of drugs,” NYPD Chief of Detectives Joseph Kenny said during a late-night news conference.

“Tonight is every parent’s worst nightmare,” NYPD Commissioner Edward Caban said of the incident. “These children don’t deserve this.”

Two of the kids were in cardiac arrest when first responders arrived at the facility, with 21-month-old Nicholas Dominici and a 2-year-old boy being given multiple doses of the overdose-reversing drug Narcan, authorities said.

Nicholas later died at Montefiore Hospital.

The two-year-old is in critical condition, sources said Saturday. The surviving boy’s younger sibling, an 8-month-old girl, was also given a dose of Narcan and is in stable condition.

A neighbor described the chaos as first responders attempted to save the children.

Alex Perez told The Post he saw “mad ambulances, cop cars, ambulances.  I thought someone got shot. I heard sirens. It was flooded. …I see them rushed out and pumping a baby. Everybody knew the baby died already because he was unresponsive.

“While they were running out, they were pumping at the same time. They were really trying,” said Perez, 32.

“I see them rushed out and pumping a baby. Everybody knew the baby died already because he was unresponsive.”

“While they were running out, they were pumping at the same time. They were really trying.”

The child’s face was purple, Perez said.

“He was on a gurney, the little one. … The ambulance guy he was getting a little impatient. I guess he also knew that the baby was like passing,” the neighbor said. “They ended up, carrying him off the thing to run to the ambulance. Someone pulls him off the gurney into his arms, and rushed the baby to the ambulance and they left right away.”

A fourth child picked up from the daycare center just before 1 p.m. Friday also appeared to have been exposed to drugs, officials said.

His mother rushed her 2-year-old son to Bronxcare Hospital when she realized the child, who had appeared to have been sleeping, was unresponsive.

He was given a dose of Narcan and revived.

The daycare, which is allowed to care for up to eight children between the ages of six weeks and 12 years old, was licensed in May, records show.

It passed an annual, unannounced inspection with zero violations just last week.