Updated 6:56 p.m. ET on 4/10/17: Hours after the shooting occurred, the Associated Press reported an 8-year-old student who was shot in the San Bernardino classroom has died. 

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At least four victims have been reported following a shooting at an elementary school in San Bernardino, California. The shooter "walked on to the North Park Elementary School campus in San Bernardino and opened fire" Monday in what law enforcement officials believe was a possible murder-suicide, KTLA reported Monday. Two adults—one man, one woman—were found dead inside a classroom. Two students were also injured, with police telling reporters at a press conference they were currently in critical condition. One victim is believed to have been a teacher. At the time of this writing, the threat was reported as having been neutralized.

Local authorities responded to North Park after reports of an active shooter around 10:30 a.m. PT, a San Bernardino City Unified School District spokesperson told KTLA. The two injured students were transported to a nearby hospital. The age of the victims, including the two injured students, was not immediately known.

"Two adults are deceased in a classroom, believed to be a murder-suicide," San Bernardino Police Chief Jarrod Burguan tweeted. "We believe the suspect is down and there's no further threat." As of 11:30 a.m. local time, Burguan said police operations were still working to secure the area. "However," he added, "we do believe the threat is down."

California Lt. Governor Gavin Newsom, in a brief statement to Twitter shortly after news of the shooting broke, said schools should be a place for "learning and community, not violence."

North Park will remain closed for "at least" two days due to an investigation.

This story will updated as more information becomes available.