JERSEY CITY, N.J. — A 4-year-old boy has died after he was found unresponsive at a New Jersey preschool.

School staff at the Cordero School PS 37 in Jersey City found the boy unresponsive after he took an afternoon nap Thursday.

The boy was rushed to a hospital, where he was pronounced dead.

Principal Derek Stanton said in a letter to parents that there will be grief counselors at the school Friday. The boy’s name has not been released.

An investigation into the boy’s death is ongoing.