One person was killed and three others were injured Wednesday night at a high school graduation ceremony being held at Fairfield High School in Fairfield, officials said.
The shooting occurred during Sem Yeto High School's graduation, which was being held at Fairfield High, and Mayor Alma Hernandez of neighboring Suisun City wrote on Facebook that the victims were shot at Schafer Stadium and that a search for the shooter was underway.
A Fairfield-Suisun Unified School District spokesperson said the shooting happened after the ceremony had ended.
The Solano County Sheriff's Office said it was assisting Fairfield police with the investigation.
Police said one of the injured was an 11-year-old; the condition of the victims was not yet known, and a suspect description was not available.
Sem Yeto is a continuation high school and shares a physical campus with Fairfield High.
Anyone with information on the incident was urged to contact Fairfield police.