A high-ranking NYPD officer fatally shot himself in Queens Monday, police sources tell.

The 43-year-old deputy inspector called his second-in-command Monday and said he was thinking about killing himself, sources said.

Concerned, the other high-ranking cop immediately called the NYPD’s Technical Assistance Response Unit to try and locate the deputy inspector’s phone, but he had already shot himself, sources said.

Cops found him dead in his department vehicle on the corner of Underhill Ave. and 164th St. across from Kissena Park just after 5:10 p.m., sources said.