U.S. Sen. Dianne Feinstein, the longest-serving woman senator in the country's history and the first woman to be San Francisco's mayor, has died at the age of 90, her office confirmed Friday, Sept. 29.

“Senator Feinstein never backed away from a fight for what was just and right. 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,” James Sauls, Feinstein's chief of staff, said in a statement.

Feinstein, who was first elected to the U.S. Senate in 1992, was a trailblazing politician -- the first woman to be president of the San Francisco Board of Supervisors who became mayor in 1978 after the assassination of Mayor George Moscone and Supervisor Harvey Milk.

The senator's legacy of legislation included the enactment of a federal assault weapons ban in 1994, the creation of the nationwide Amber Alert network for missing children, and the release of a report into the CIA's detention and interrogation practices that led to the passage of laws to ensure that some post-Sept. 11 interrogation methods would never be used again.

Gov. Gavin Newsom, himself a former San Francisco mayor, was among the local politicians to issue statements Friday morning mourning Feinstein's death. Her passing means that Newsom will now be charged with appointing her replacement.

"Dianne Feinstein was many things -- a powerful, trailblazing U.S. Senator; an early voice for gun control; a leader in times of tragedy and chaos. 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," Newsom wrote.

Other local public officials issued statements in reaction to Feinstein’s death on Friday.

“Senator Feinstein was a trailblazer for women in politics [and an icon in California who overcame adversity (and) tragedy and dedicated her life to service to others.” wrote Assembly member Marc Berman in a statement on X, the social media site formerly known as Twitter. “Before we speculate about the future, I hope everyone takes the time to honor her remarkable life.”

State Sen. Josh Becker also lauded Feinstein for her many years of leadership.

"She entered Congress and went to work on some of the major issues facing our nation, including gun safety and LGBTQ+ rights," Becker said in a statement on X. "She served CA (with) dignity and helped cement CA's influence nationwide. Sen. Feinstein will be missed."

Assembly member Diane Papan said that Feinstein would leave an “indelible mark on the history of our nation, our state and our region.”

“Her legacy is palpably felt in our made and natural environments thanks to her policy achievements and by every woman who has ever run for office due to her shattering of many glass ceilings. She will be greatly missed,” she said.

California Senator Scott Wiener (D-San Francisco) issued the following statement in response to the passing of Feinstein:

“Dianne Feinstein was a true giant. She helped save our city, becoming Mayor after horrific political assassinations [and leading us during the worst of the HIV/AIDS health disaster. As our Senator, she led on gun safety [and so many issues.

"There will never be another Dianne Feinstein,” he added.