Large crowd at City Hall urging shutdown of Juve Hall..⁦@abc7newsbayarea⁩ pic.twitter.com/15mTWkX4lf — Vic Lee (@vicleeabc7) April 9, 2019

SF Supervisor Shamann Walton was once incarcerated at Juvenile Hall as a young man. He spoke in support of shutting down the Hall. pic.twitter.com/fLLMPdWiHT — Vic Lee (@vicleeabc7) April 9, 2019

Proponents of shutting down Juve Hall say it’s too expensive and doesn’t rehab young offenders. pic.twitter.com/XU1zr6aN8Y — Vic Lee (@vicleeabc7) April 9, 2019

Rally at City Hall to shut down SF Juvenile Hall. pic.twitter.com/0aRfQnBJ68 — Vic Lee (@vicleeabc7) April 9, 2019

SAN FRANCISCO (KGO) -- A group of San Francisco Supervisors are threatening to shut down the city's juvenile hall, saying it makes "economic and social sense."They're introducing legislation Tuesday at the board meeting that would close the 150-bed facility.Some 200 people gathered for a rally outside City Hall to shut down the 150-bed facility in Diamond Heights on Tuesday.Six of 11 San Francisco supervisors have declared their support for a measure that will be introduced at Tuesday's board meeting.It's a measure that will close the facility while launching a task force to come up with secure and supportive alternatives for young offenders.As a young man, Supervisor Shamann Walton was incarcerated in a juvenile detention facility for armed robbery and other crimes. He says the changes in his life were all through mentorships. "Education exposure, quality after school programs. It has never been because of time spent in juvenile hall," he said.Among speakers on Tuesday was youth activist Fernando Madrigal, who spent time at San Francisco juve hall for robbery when he was 13."I was locked in my cell for one month straight. One month straight. Thirty minutes out in the morning. Thirty minutes out in the night shift," Madrigal remembers.He said the incarceration made him angry and depressed.Those who want juve hall shut down say its population has dropped dramatically, leaving 70 percent of the facility empty.They also point to the cost of incarceration -- about $250,000 dollars per young person.Chief Juvenile Probation Officer Allen Nance credits the drop in juvenile crime to the city's progressive programs."Are there opportunities for further reforms? Absolutely," he says. "Although I would like to have those reforms in place before there is a commitment to shutting down existing juvenile hall."Reverend Amos Brown, head of the city's NAACP, is also against the shutdown. "You have young people who are not reared by parents, who need discipline who need structure. They need a quality facility such as juvenile hall," he says.So far, supporters of the legislation say they have six of the eleven supervisors on the Board. But to be safe, they need eight votes to override a mayoral veto.And Mayor London Breed has said she does not support the legislation in its present form.She wants to appoint a blue ribbon committee to look into alternatives first before considering closing the facility.