Former San Bernardino City Unified school board member Judi Penman said the school's police department "is very well prepared" for situations such as the shooting Monday at North Park Elementary.
The city of San Bernardino was the scene of a shooting rampage on December 2, 2015, when a husband and wife killed 14 people and wounded more than 20 others at a holiday office party.
Maria Garcia says the shooting is believed to have stemmed from a domestic dispute.
Mr Sherwin said numerous firefighters and police officers are attending the scene.
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Two students have been taken to hospital.
Pupils were being taken to a local college campus, Ms Garcia said. Students gathered on a field and a blacktop basketball court inside the fenced-in grounds of the campus near a line of school buses. One of them was a teacher, the other was an unidentified man. "I hope she is OK", Hendran said.
San Bernardino Mayor Carey Davis said he received a call from the White House expressing concern for the students and teachers at the school. The shooting happened at North Park Elementary School, just before 2 p.m. ET.
Students were evacuated to the nearby Cajon High School.
- Chief Jarrod Burguan (@SBPDChief) April 10, 2017Chief Jarrod Burguan also tweeted that two adults "are deceased in a classroom. We do not know how that suspect gained access into our school". The shooters were later killed in a shootout with police.