A 16-year-old boy who had been waiting to see an administrator about a disciplinary issue jumped to his death from a private, tuition-free all-boys’ Upper East Side high school building early Thursday, cops and sources said.

The teen plunged from a fifth-floor window at Regis High School, a Catholic, Jesuit school on East 84th Street near Madison Avenue, around 9:30 a.m., police said.

He was found outside the building “with injuries indicative of falling from an elevated position” and was rushed to Weill Cornell Medical Center, where he was initially listed in stable condition, authorities said.

His condition took a rapid downturn and he was pronounced deceased around 11:45 a.m., cops said.

Before the deadly incident, the boy was waiting outside a school official’s office on the first floor for an undisclosed disciplinary issue, sources said.

He then walked up to the fifth floor, where he jumped, according to the sources.

His identity was not immediately released pending family notification.

An ambulance with its lights flashing on a street in front of New York Presbyterian Weill Cornell Medical Center.

Hours later, a man wearing a black shirt with a priest collar seen walking out of the school would only say “someone had an accident” and was “seriously injured.”

A woman who lives nearby said she spoke to a parent of one of the Regis students who received notification that “there was an incident” at the school and everyone was being sent home.

Regis High School is “tuition free and merit based, giving special consideration to families in need of financial assistance,” according to its website.

Its 540 students from grades 9 through 12 commute from 219 zip codes across the city, and 52 percent of the students are sons of immigrants.

Three Jesuit priests and 56 lay men and women are on the faculty.

If you are struggling with suicidal thoughts or are experiencing a mental health crisis and live in New York City, you can call 1-888-NYC-WELL for free and confidential crisis counseling. If you live outside the five boroughs, you can dial the 24/7 National Suicide Prevention hotline at 988 or go to SuicidePreventionLifeline.org.