Washington police chief Cathy Lanier, the first woman to lead the department and one of the nation's longest-serving and most popular big-city police chiefs, announced Tuesday that she is stepping down to become head of security for the National Football League.

Lanier, 49, started her career with the Metropolitan Police Department as a patrol officer and rose through the ranks. She served as chief for nine-and-a-half years, under three mayoral administrations, overseeing reductions in crime as the nation's capital experienced an influx of wealth that transformed once-troubled neighborhoods.

Lanier said at a news conference that she has rejected numerous offers to lead other big-city police departments, but she saw the opportunity to handle security for the nation's "favorite sport" to be too good to pass up.

"To women who think that there are limitations to what you can do and where you can work, the NFL reaching out to me for this position says that there are not limitations for where you can work because of your age, your race or your gender," Lanier said.

In her new job, Lanier will oversee the security of all 32 NFL teams and their venues, working with federal, state and local law enforcement and handling security for the Super Bowl.

"We are excited to welcome to our team an individual of Cathy's talent and extensive record of accomplishments," NFL Commissioner Roger Goodell said in a statement. "Cathy joins us with a well-deserved reputation of being a tremendous communicator, innovator and relationship builder."

Lanier, a Maryland native who dropped out of high school in 9th grade and became a mother at age 15, was an inspiration to many as she rose to the department's top job. She came from a family of police officers and joined the department after earning a high-school equivalency diploma. She later earned a bachelor's degree and two master's degrees.

Lanier was head of homeland security and counterterrorism for the department when then-Mayor-elect Adrian Fenty called and offered her the job of chief, without an interview.

"This city gave me an opportunity when many would not have," Lanier said. "I owe my life to this city, to the residents and to the department. ... It's bittersweet, it's heartbreaking to leave the city I grew up in."

Polls consistently ranked her as the most popular public official in the city, and she had a frank, easygoing manner on television and in testimony before the D.C. Council. She was an early advocate of officers wearing body cameras, saying they would increase transparency and promote good policing. The department is in the process of outfitting all patrol officers with cameras.

Washington was dubbed the nation's murder capital during the crack epidemic of the 1990s — with more than 300 slayings a year in the city of roughly 600,000 — but violent crime had already decreased significantly by the time Lanier became chief amid the city's booming post-9/11 economy. Homicides continued to drop to a low of 88 in 2012, although, slayings increased last year by more than 50 percent, and killings this year are continuing at 2015's pace.

Lanier said she was most proud of restoring the department's commitment to community policing.

"The most important legacy is we have a community that supports us," she said. "People will talk to us now and give us the information we need."

Lanier clashed periodically with the city's police union, particularly over a wave of retirements that some officers said left the department — which now has 3,700 officers — dangerously understaffed. Union treasurer Gregg Pemberton said nearly 1,000 officers had "fled" the department in the past two-and-a-half years.

"Lanier should be ashamed that she's leaving the department in disarray," Pemberton said. "Morale has never been worse."

Lanier's last day will be Sept. 17. Democratic Mayor Muriel Bowser said she will appoint an interim chief in the coming days, and she said it's possible the next permanent chief will be promoted from within.

"The National Football League, you've got a good one here," Bowser said. "She leaves the department and the city in very good hands."

Lanier made $253,000 annually as police chief. Because her departure is considered a retirement, she will receive an annual pension of roughly $177,000. She declined to disclose what her salary with the NFL will be.