Health experts are urging New Yorkers to prepare themselves for emergency overdoses after fentanyl was detected in the system of four Bronx children resulting in the death of one child.

The NYPD says they are now searching for the husband of that day care owner after discovering a kilogram of the drug near sleeping mats where those children were napping last week.

Two other people are already in custody for the crime, including the owner Grei Mendez, and Carlisto Acevedo Brito. They're both facing more than 10 charges each, including murder for the death of 1-year-old Nicholas Dominici, who died after being exposed.

First responders say they were able to save the lives of the other children using Narcan, an overdose reversal medicine that experts say should be accessible to everyone.

"There's an importance for the city, that should come with certification of these days care centers and nursing homes," said Eugene Vortsman, the clinical director of addiction medicine and disease management at Northwell Health. "The teachers and the doctors [should] all be educated on how to safely use this medication and be able to save that life," he said.

That lifesaving medicine can be bought at many pharmacies across the city and is offered for free at certain community programs.