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LOS ANGELES — A 12-year-old girl remains in juvenile hall and was booked for negligent discharge of a firearm after Thursday’s shooting at a Los Angeles middle school.

The shooting, which left four students and an adult injured at the Sal Castro Middle School, is being considered “unintentional,” said Los Angeles Police Department spokesman Tony Im.

Detectives are continuing to investigate the shooting. Lt. Chris Ramirez with the LAPD said negligent can mean many things, but most likely a “mishandling.

“This continues to be an active investigation,” according to a LAPD statement. “However, at this time, the information suggest that this was an isolated incident, involving the negligent discharge of a firearm, where innocent children and a staff member were unfortunately injured.”

The girl has been taken to the Los Angeles County Central Juvenile Hall. Police didn’t say what led to the shooting and little information was released about the girl who was detained. She was taken into custody without incident, officials had said.

Meanwhile, the middle school, which is in the city’s Westlake district, will have classes Friday.

Injured, but expected to recover

The shooting was reported to police Thursday at 8:55 a.m. It happened in an elective class with students from different grades, said the LA School Police Chief Steven Zipperman.

The 12-year-old girl and witnesses were being interviewed, he said Thursday.

The victims include a 15-year-old boy who was shot in the head, but is expected to recover, said officials at Los Angeles County + USC Medical Center. He was shot in the temple and was “extremely lucky” in that the bullet missed vital structures, said Dr. Aaron Strumwasser, a trauma surgeon. The student remains in intensive care.

A 15-year-old girl who was shot in the wrist was also hospitalized. Two other students, ages 11 and 12, suffered graze wounds, were treated and released, Strumwasser said.

A 30-year-old woman suffered a minor injury in the chaos after the shooting, officials said.

A student reacts as parents arrive on campus after school to pick up their children at Sal Castro Middle School in Los Angeles, California on February 1, 2018.
Two 15-year-old students in Los Angeles were shot and wounded in class at the school Thursday, in the latest school shooting to hit the United States, reigniting the long-running debate over gun control. A boy was shot in the head, while a girl was hit in the wrist, emergency services personnel said, confirming that a 12-year-old girl was arrested over the incident.
/ AFP PHOTO / Frederic J. Brown (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)

On Thursday, after the campus was declared safe, the school day continued and students had the chance to talk to counselors about the shooting, said Vivian Ekchian, interim superintendent of the Los Angeles Unified School District.

Police confiscated a gun at the scene. Ramirez said the weapon was a semiautomatic.

Questions of how and why the gun ended up at the school remain.

The grandmother of the 12-year-old girl spoke briefly with CNN affiliate KABC. She was not identified, but told the station that her granddaughter was caring and loving, but didn’t have many friends and had been bullied by another girl.

A student reacts as parents arrive on campus after school to pick up their children at Sal Castro Middle School in Los Angeles, California on February 1, 2018.
Two 15-year-old students in Los Angeles were shot and wounded in class at the school Thursday, in the latest school shooting to hit the United States, reigniting the long-running debate over gun control. A boy was shot in the head, while a girl was hit in the wrist, emergency services personnel said, confirming that a 12-year-old girl was arrested over the incident.
/ AFP PHOTO / Frederic J. Brown (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)

Third school shooting

In the first month of 2018, there were two other shootings at middle or high schools that resulted in death or injury:

On January 23, a 15-year-old student shot 16 people — killing two other 15-year-olds — at Marshall County High School in Benton, Kentucky, authorities said. The student faces two charges of murder and 12 counts of first degree assault, authorities said.

Bailey Holt died on the Marshall campus in western Kentucky. Preston Cope died at a hospital.

On January 22, a 15-year-old student was injured in a shooting at a high school in Italy, Texas, authorities said. The suspect, a 15-year-old, was quickly apprehended.

And that’s only the shootings at middle or high schools — other shootings have occurred on campuses this year, including the fatal shooting of a Winston-Salem State University student at Wake Forest University last month.

Two other shootings occurred near high school buildings in January.

On Wednesday, a 32-year-old man was shot and killed in a parking lot outside a Philadelphia, Pennsylvania high school during a basketball game, according to CNN affiliate WPVI. The station said 911 calls came in reporting a large fight and shots fired.

In New Orleans, Louisiana, shots were fired at students who were outside for lunch last week, CNN affiliate WDSU reported. One student suffered an abrasion on his elbow, according to CNN affiliate WVUE.