Four people, including a teacher and two students, have been shot at an elementary school in San Bernardino, California. One student is in stable condition, while the other three people were killed. The incident is believed to have been a murder-suicide, according to police. The shooting stemmed from a domestic violence situation.

Police have confirmed the shooter as Cedric Anderson, 53, who shot and killed himself after shooting and killing his wife, teacher Karen Elaine Smith, 53. Two students standing behind Smith were also struck. 8-year-old Jonathan Martinez died after being airlifted to a hospital. An unnamed 9-year-old boy is currently in stable condition.

The weapon was described as a "large caliber revolver."

San Bernardino Police Chief Jarrod Burguan confirmed in an afternoon press conference that the first report of the shooting came in at 10:27am, and that the first units of police arrived at North Park Elementary School at 10:34am, where eight police officers entered a special needs classroom, the sole location of the shooting.

Burguan told reporters that the shooter entered the school through the front office, telling employees that he was there to drop something off for his wife.

Suspect in shooting identified as Cedric Anderson, age 53, resident of Riverside, CA. pic.twitter.com/H9YYQZvZud — San Bernardino PD (@SanBernardinoPD) April 10, 2017

The classroom had 15 students of grades 1st through 4th.

The shooting occurred in a classroom at North Park School. Along with the three victims, the suspect is believed to be down as well, according to San Bernardino Police Chief Jarrod Burguan.

We believe this to be a murder suicide. Happened in a class room. Two students have been transported to the hospital. — Chief Jarrod Burguan (@SBPDChief) April 10, 2017 Two adults are deceased in a classroom, believed to be a murder suicide. We believe the suspect is down and there's no further threat. — Chief Jarrod Burguan (@SBPDChief) April 10, 2017

Two adults ‒ a man and a woman ‒ are dead in the classroom, and police “believe the suspect is down and there's no further threat,” Burguan said.

The gunman checked in with the front office, where he was known to school staff, San Bernardino Police Captain Ron Maass said.

Patricia Brown waits to pick up her daughter at North Park Elementary in San Bernardino where there was an active shooter pic.twitter.com/baqvwhelIf — Rick Sforza (@RickSforza) April 10, 2017

The two students were transported to the hospital, one via helicopter and the other in an ambulance, a police spokesman told reporters. They are in critical condition.

"The children we do not believe were targeted," the spokesman said.

BREAKING: Students hold hands while evacuating North Park Elem, in #SanBernardino after apparent murder-suicide on campus. 2 students hurt pic.twitter.com/zvuALVuk6F — Val Gratias (@valeriegratias) April 10, 2017

The fire department has set up a triage to assess and treat victims at the scene. Law enforcement was on the scene within seven minutes of the shooting.

The San Bernardino County Sheriff’s Department is assisting in the investigation. The school will be closed for "at least" the next two days, police said.

#BREAKING San Bernardino school spokeswoman says 1 of 4 shot in classroom was teacher. https://t.co/frni4l1aY3pic.twitter.com/CwntJB0kB3 — WPEC CBS12 News (@CBS12) April 10, 2017

North Park, Cajon and Hillside Elementary Schools are on lockdown, while the San Bernardino campus of California State University is under a shelter-in-place order.

Students were evacuated to Cal State San Bernardino, while parents were told to pick them up at Cajon High School. They must be listed on the students' emergency contact forms and show photo ID.

District employee Jacqulyn Bowles hands out forms to parents that must be filled out to pick up their children at Cajon HS in San Bernardino pic.twitter.com/QFeJ5jpvn7 — Maya Lin Sugarman (@mayasugarman) April 10, 2017

This is the second mass shooting in the southern California city in since December 2015. In that incident, which was later categorized as an act of terrorism, a married couple opened fire on a holiday party for the husband’s work, killing 14 and injuring 21.

Initially had a replay of the deeply disturbing feeling of terror and dread felt on Dec2nd 15 when I turned scanner on today. #PTSDAwarenesshttps://t.co/ee0XzukcXb — Darren Espiritu (@SBDarren) April 10, 2017

"Tragedy has struck us again, and we need to now work through that and be there for all of the involved parties," the San Bernardino PD said.

San Bernardino experienced a surge in violence in 2016, including a 41 percent increase in homicides over the previous year. The 62 slayings made 2016 the city’s deadliest year since 1995, the Los Angeles Times reported.

The White House contacted San Bernardino Mayor R. Carey Davis, he told reporters. Education Secretary Betsy DeVos tweeted her support.