At least six people were wounded in a shooting at a school in Oakland on Wednesday, officials said.
The shooting was over, Alameda County Sheriff spokesman Lt Ray Kelly said.
Paramedics took six patients to hospitals, all with gunshot wounds, Oakland Fire Department spokesman Michael Hunt said.
Oakland Mayor Libby Schaaf tweeted that all of the wounded were adults and the shooting happened at Sojourner Truth Independent Study, an alternative K-12 school.
Officials did not say if any of the victims might be pupils aged 18 or older.
Three of the wounded were in critical condition at Highland Hospital in Oakland and the other three were taken to Eden Medical Centre in Castro Valley. Their conditions were not known, officials said.
John Sasaki, a spokesman for Oakland Unified School District, said that district officials “do not have any information beyond what Oakland Police are reporting".
He said the Sojourner Truth Independent Study headquarters has no pupils and is in the same block as three other schools.
TV footage showed dozens of police cars and yellow tape on the street outside the school and pupils leaving nearby campuses.
City Council Member Treva Reid said investigators told her the shooting might be tied to rising "group and gang violence".
Oakland Police Capt Casey Johnson confirmed that six people were shot but would not answer any questions.
City Council Member Loren Taylor, who was outside the school, declined to confirm any details about the incident, telling KTVU-TV: "Guns were on our school campuses where our babies were supposed to be protected."