The shooting at Sal Castro Middle School that left five people injured on Thursday morning was accidental, Los Angeles police officials 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.

Jordan Valenzuela, a student at Sal Castro, told the Associated Press that he was in class when he heard a loud bang and then screaming. He told AP that the 12-year-old girl, his classmate, told him it was an accident, saying, I didn't mean to. I had the gun in my backpack and I didn't know it was loaded and my backpack fell and the gun went off.'

On Thursday evening, the girl was booked into Juvenile Hall on suspicion of negligently discharging a firearm, AP reported.

On Friday morning, LAPD officials addressed parents at the school. They tweeted, Our Los Angeles Officials from @LASchoolPolice @LASchools @LAPDRampart are addressing parents of yesterday's incident and ensuring our priority is the safety of their children here at Sal Castro Middle/Belmont High. We advise everyone: If you see or hear something, say something.

In the tweet, police did not address the questions many parents and others have: how a 12-year-old girl was able to get her hands on a gun in the first place, and how she was able to get it out of her house and into her school.

As a parent, this is everyone's worst-case nightmare ? a worst-case scenario and a nightmare for all of us, Robert Arcos, commanding officer of the Los Angeles Police Department's Operations-Central Bureau, told reporters Thursday.

With students returning to class on Friday, the incident will, and should, raise more questions about gun control in California, and the country.