At least two adults were killed in a San Bernardino North Park Elementary School classroom in what is believed to be murder-suicide, San Bernardino Police Chief Jarrod Burguan tweeted.
The authorities believe the suspect is down and there is no further threat, Burguan said, the CNN reported.
The two students at the school were transported to a hospital after the shooting that took place in a classroom.
The police chief said the incident appears to be a murder-suicide.
Preliminary information shows four victims are being treated and the suspect is possibly down.
San Bernardino City Unified School District will release a statement shortly.