San Francisco Mayor Ed Lee died early Tuesday morning at the age of 65, his office said in a statement, adding that London Breed, the board of supervisors president, will become the city's acting mayor.

“It is with profound sadness and terrible grief that we confirm that Mayor Edwin M. Lee passed away on Tuesday, December 12 at 1:11 a.m. at Zuckerberg San Francisco General Hospital. Family, friends, and colleagues were at his side. Our thoughts and prayers are with his wife Anita, his two daughters, Brianna and Tania, and his family,” his office said.

Lee was San Francisco’s 43rd mayor.

After Lee's death, Breed will be taking over his position effective immediately, his office said. Breed serves as the supervisor for District 5 which includes neighborhoods of Inner Sunset, Haight Ashbury, Lower Haight, Fillmore, Western Addition, part of Cathedral Hill, Parnassus Heights, North Panhandle, Anza Vista, Lower Pacific Heights, Japantown, Hayes Valley, part of Ashbury Heights, and part of UCSF Parnassus Heights.

London also serves on the Golden Gate Bridge Board of Directors, as a Commissioner on the San Francisco County Transportation Authority, and is an elected member of the San Francisco Democratic County Central Committee.

Born Aug. 11, 1974, Breed was first elected to the District 5 in November 2012 after she defeated Christina Olague. Breed's win with over 12 points made her the first challenger who unseated a district supervisor.

In February 2016, she announced her re-election bid and won by beating Dean Preston, an attorney.

"I'm working to ensure that every San Franciscan has the opportunity of a good-paying job, a safe, dignified place to live that fits a working person’s budget, improved environmental health, more reliable public transportation, and the peace of mind that comes from feeling safe in our homes and on the streets of our City," a message on her website reads.

According to her website, London was raised by her grandmother in Plaza East Public Housing in the Western Addition community, located in District 5. She graduated from Galileo High School and attended the University of California, Davis, earning a Bachelor of Arts in Political Science-Public Service with a minor in African American Studies. She also has a Master’s degree in Public Administration from the University of San Francisco.

In 2015, Breed gave out a strong message for the African American community regarding gun crime saying: “When you know your kids are involved in this violence, let’s turn them in… If we are going to change the problems, we have to look inside our own homes and see if we have problems with our own children.”

Her remarks came just days after four young African-American men were fatally shot in a stolen car at the corner of Laguna and Page streets, part of the Hayes Valley neighborhood that Breed represents on the board.

Social media reacted to Lee's sudden death, but some also expressed their views about Breed becoming the acting mayor.