The gunfire erupted just before 9 a.m. PT at Salvador Castro Middle School, just west of downtown Los Angeles.
One student seemed to corroborate that description, telling the Los Angeles Times he thought the shooter was "playing" with the firearm.
"They thought it was a toy gun, but then it shot", Urbina said.
The LAPD took a 12-year-old girl into custody but determined that the incident was an accident after questioning her, officials said in a statement Friday. A 30-year-old woman was also injured in the melee.
"I'm anxious about the kids who got shot", he said. The bullet went through the wrist of the girl and struck the boy in the head, the LAPD said.
In the immediate aftermath of the shooting, officers could be seen bringing several students out of a classroom with their hands behind their backs, aerial footage showed.
The incident occurred around 9am Thursday morning at Sal Castro Middle School, which is located on the campus of Belmont High School, Los Angeles School Police said, and placed the campus on lockdown for almost five hours.
Chris Long talks Tom Brady, underdog support with Good Day
Both are battling Father Time, but the QB and small forward are still regarded as the best in their corresponding sports. Another component to winning against the Patriots is to stay in the lead until the game's final few seconds, he said.
Steven Zipperman, chief of the Los Angeles School Police department, called the incident "very traumatic" for the kids in the classroom.
"She doesn't do bad things, she just stays quiet", he added.
"Not safe, very insecure", Anzueto said of the school.
Mayor Eric Garcetti told local news channel KABC-TV at the scene that it was unclear if the shooting was accidental. A lot of anxious parents and relatives were waiting outside the campus. Police still don't know where she got the unregistered gun.
The girl told her classmate that the gun was in her backpack and that it accidentally discharged when she dropped her bag.
Arcos said that the 12-year-old has an attorney and is not talking to investigators. Westlake, a mostly Hispanic area, is home to more than 20 schools. Some schools failed to do the searches daily, the audit found. One-fourth lacked enough metal-detecting wands to search properly.The district started random searches in 1993 after a 16-year-old was shot and killed at Fairfax High School.
The enrollment is 92 percent Latino, and most students are from low-income families.