Billionaire financier and investor Thomas H. Lee was found dead of a self-inflicted gunshot wound at his Manhattan office on Thursday morning, police sources said.

Cops responded to a 911 call at 767 Fifth Avenue — where Thomas H. Lee Capital, LLC is located on the sixth floor — at around 11:10 a.m., the sources said.

EMTs pronounced the 78-year-old businessman dead at the scene.

The Office of the Chief Medical Examiner will determine the official cause of death.

A woman who answered the phone at Lee Equity Partners declined to comment Thursday afternoon.

A man who answered the phone at a number listed for Lee’s wife, Ann Tenenbaum, at an address in the Sutton Place neighborhood said: “We have no comment.”

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.