(CNN) Three members of the New York Police Department have died by suicide in less than 10 days, Police Commissioner James P. O'Neill said Friday.

Last week, a respected chief and an experienced detective died within 24 hours of one another, O'Neill said. Friday, a "promising 29-year-old police officer with six years on the job" died behind the NYPD precinct in Staten Island, where he worked, the commissioner said.

"This is a mental-health crisis. And we -- the NYPD and the law enforcement profession as a whole -- absolutely must take action," O'Neill said in a statement. "This cannot be allowed to continue. Cops spend so much of their days assisting others. But before we can help the people we serve, it is imperative that we first help ourselves."

This is a mental-health crisis. And the NYPD & the law enforcement profession as a whole absolutely must take action. We must take care of each other; we must address this issue — now. Please take my statement below to heart & help yourself, your loved ones, & your colleagues. ⬇️ pic.twitter.com/urHuzIiiFb — Commissioner O'Neill (@NYPDONeill) June 15, 2019

This week, O'Neill asked members to "connect yourself or your friends and colleagues to the assistance that is so close by. We must take care of each other. We must address the issue -- now --- because it will not go away on its own. We must speak out. And we must end this crisis, together."

Commissioner's open letter

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