A Queens teenager mysteriously died in the middle of basketball practice Wednesday, sources said.

Lenny Pierre, 16, collapsed inside John Bowne High School in Queens just after noon, according to police.

The 6-foot-6 junior was practicing with the school’s Wildcats basketball team, a source said.

He was rushed to New York Presbyterian Hospital-Queens but pronounced dead there, cops said.

Distraught coach John Tsapelas declined to comment.

“Not right now,” he said, when reached by phone.

Mayor Bill de Blasio lamented the death.

“I am heartbroken to hear of Lenny Pierre’s passing. As a parent, and as a father of student athletes, I can only imagine the pain and sorrow being felt by Lenny’s family, loved ones and classmates,” de Blasio said in a statement. “On behalf of 8.6 million New Yorkers, I extend our deepest condolences. We will be with this family now and in the future as we mourn the loss of one of our City’s children.”

An investigation is ongoing, police said.

Read more on the New York Post.