(CNN) A fourth New York City police officer has killed himself this month, New York police said Thursday. It's the latest death in what the city's top cop has called a "mental-health crisis."

The 53-year-old officer died of a self-inflicted gunshot wound during a family gathering in his Hicksville, New York, home on Wednesday night, according to two law enforcement officials.

The 24-year NYPD veteran worked the midnight shift at the 50th Precinct in the Riverdale section of the Bronx, the officials said. He was on vacation at the time and due back to work on Sunday, they said. He leaves behind a wife and three children.

It was the department's sixth death by suicide this year -- the fourth since June 5 -- and the 101st involving law enforcement across the nation in 2019, Chief of Department Terence Monahan said Thursday.

"We have to be willing to talk if people have a problem, to come forward and, more importantly, we have to be willing to listen," he told reporters.

"We're looking at what we can do as a agency. How we can handle this better. How we can help out people. Cops run out day in and day out and save peoples lives that they don't know. We have to figure out how to save our own lives."

On June 14, after a "promising 29-year-old police officer with six years on the job" died behind the Staten Island precinct where he worked, Police Commissioner James P. O'Neill appealed to members of the nation's largest police force to seek help.

"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."

At the time, three police officers had died by suicide in less than 10 days, including a respected chief and an experienced detective who died within 24 hours of one another, police said.

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

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."

There is no "easy answer" to the problem, Monahan said.

"We do everything we can -- give them vests, do every training we can to keep them safe out on the street when they're keeping the members of New York City safe," he said. "We need to find a better way to keep them safe from themselves."

Asked whether an officer faces reassignment or losing access to their weapon after seeking help, Monahan said: "Listen, first off, I don't know if anyone wants someone ... in the middle of a crisis, contemplating suicide, to have a gun on their side at that moment. But when they come back to full duty, when they've been treated, when they feel better, this is what we have to do better as an agency."

Commissioner's open letter

O'Neill said the NYPD has averaged about four or five suicides each year over the last five years.

Earlier this month, the commissioner made a similar appeal in an open letter he sent to members of the his department.

"Seeking help is never a sign of weakness -- it's a sign of great strength. Trained members will listen and connect you with even more help, around the clock. I implore you to seek out -- or to help others find -- the assistance that is so readily available to us all," the letter said.

New York City Mayor Bill de Blasio also issued a statement at the time: "I want every member of the NYPD to know: your city is here for you. You are not alone. Help is here. Reach out. We are working with the Police Department to continue to put resources front and center, and that our officers have every possible support."

Study finds barriers

A 2018 study by the Ruderman Family Foundation , a philanthropic organization, found policemen and firefighters are more likely to die by suicide than in the line of duty. But there are several barriers preventing first responders from accessing mental health services, "including shame and stigma," the paper states.

"These same barriers prevent families from talking openly about the suicide of a loved one, thereby contributing to silence and lack of awareness around the issue of first responder suicide," according to the study.

"We need to end the silence that surrounds the issue of first responder mental health. We should celebrate the lives of those lost to suicide -- at national monuments such as the National Law Enforcement Memorial, in the media, and within police and fire departments around the country," Ruderman Family Foundation President Jay Ruderman said in a statement accompanying the study. "Also, departments should encourage or require first responders to access mental health services annually. This will enable our heroes to identify issues early, and get the help that they need. It will save lives."