California Senator Dianne Feinstein has died. She was 90 years old.

Her chief of staff announced her death in a statement Friday, saying that the lawmaker died Thursday night at her home in Washington, DC.

"Senator Feinstein never backed away from a fight for what was just and right," the statement said. "At the same time, she was always willing to work with anyone, even those she disagreed with, if it meant bettering the lives of Californians or the betterment of our nation."

"There are few women who can be called senator, chairman, mayor, wife, mom and grandmother. Senator Feinstein was a force of nature who made an incredible impact on our country and her home state," it continued. "She left a legacy that is undeniable and extraordinary. There is much to say about who she was and what she did, but for now, we are going to grieve the passing of our beloved boss, mentor and friend."

Former House Speaker Nancy Pelosi said in a statement Friday that Feinstein was a "pillar of public service in California."

"Her indomitable, indefatigable leadership made a magnificent difference for our national security and personal safety, the health of our people and our planet, and the strength of our Democracy," the statement continued.

Feinstein was the oldest member of Congress at the time of her death. She was a lifelong advocate for liberal causes including gun control, land preservation, and reproductive freedom.

Feinstein became the first woman mayor of San Francisco in 1978, after former city supervisor Dan White assassinated then Mayor George Moscone. White also killed Harvey Milk, the first openly gay person to be elected to public office in California. Feinstein was the one who discovered Milk's body.

Feinstein served as mayor for ten years and oversaw the rebuilding of San Francisco's cable car system, established funding for research on HIV/AIDS, and implemented the city's first rent control program.

But she also angered San Francisco's gay community in 1982 when she vetoed a bill that would have expanded benefits for domestic partners.

In 1992, she became the first woman to represent California in the US Senate and was one of the loudest voices on legalizing same-sex marriage.

California Gov. Gavin Newsom described Feinstein as a "political giant" in a statement released after her death.

She was "an early voice for gun control; a leader in times of tragedy and chaos," the statement said. "But to me, she was a dear friend, a lifelong mentor, and a role model not only for me, but to my wife and daughters for what a powerful, effective leader looks like."

"She broke down barriers and glass ceilings, but never lost her belief in the spirit of political cooperation. And she was a fighter — for the city, the state and the country she loved," it continued.

"There is simply nobody who possessed the poise, gravitas, and fierceness of Dianne Feinstein," it added.

Feinstein was also the first woman to chair the Senate Intelligence Committee.

When she was Senate intel chair, Feinstein made headlines for exposing the CIA's torture program.

She also had a long reputation for working across the aisle. "I don't tend to be a person who tries to pit one person against another," she told CALmatters in 2018. "I find I get more done by working together." 

Feinstein faced a number of health issues in the last year and was absent from the Senate for a period of time when she was hospitalized with shingles. Several House Democrats subsequently called on the California to resign.

"Because Sen. Feinstein was absent, Republicans are passing legislation through the Senate, undermining the right of our residents to breathe clean air," Michigan Rep. Rashida Tlaib tweeted in April. "And with a far-right judiciary targeting our human rights, we are unable to confirm judges. Sen. Feinstein must step down."