▶ Watch Video: 1-year-old dead, 3 other children rushed to hospital after incident in Bronx

NEW YORK — A 1-year-old boy has died and three other children were rushed to a local hospital after an incident at a Bronx day care Friday.

Police are still investigating what happened, but we do know Narcan was administered to the children and worked on at least one of them.

EMS responded to the day care on Morris Avenue in the Kingsbridge Heights section just before 3 p.m.

Four children were taken to the hospital in cardiac arrest. A 1-year-old boy died, while two 2-year-old boys and an 8-month-old girl are still being treated. At least one child remains in critical condition.

FDNY has ruled out carbon monoxide as a factor, and police are investigating if fentanyl was involved.

The location is a large apartment building with a day care on the first floor. CBS New York’s Ali Bauman spoke to a witness who lives in the basement apartment beneath the day care and says she heard a day care employee screaming, so she went upstairs to see what was wrong.

The witness says she saw through the open door that there were toddlers, as she described them, unresponsive on the mat in the day care. She says the worker was yelling, “They’re dying, they’re dying,” and she tried to help as an employee was carrying a child outside.

CBS New York investigative reporter Tim McNicholas looked up the building where this happened and found the state just inspected a day care there last week. It passed, and the Office of Children and Family Services found no violations there.

Those inspections include several safety checks. For example, the state noted there were no poisonous or toxic items accessible to children, and a caregiver certified in CPR and first aid was present at all times with the children.

It’s classified by the state as a “group family day care,” meaning it’s a day care being operated out of a home.

Its total capacity is for eight children, ages 7 weeks-12 years old.

The owner of the day care is being questioned. Neighbors say the day care just opened within the last year and is run by a mother and daughter.