Update 12:50: Maybe there is some credibility for the dropped backpack story.
KTLA reports: Gardena police say two students were wounded by one bullet.
A 15-year-old girl was shot in the head, She is in critical condition.
A 15-year-old boy shot in the neck. He is in stable condition.
Police with guns drawn surrounded a classroom as students walked outside with their hands in the air.
One young man was then placed on the ground and handcuffed.
The suspect, described only as a 16-year old boy dressed in dark clothing, was taken into custody shortly before noon.
Update 1:10: From NBC Los Angeles
Gardena High School Principal Rudy Mendoza said the student dropped the bag as he walked between classes at midmorning. The boy who brought the gun was apprehended, Mendoza told The Associated Press.
Police initially reported that three people were shot and the shooter was at large.
Numerous law enforcement agencies responded to the shooting at the 2,400-student campus located in the city of Los Angeles adjacent to the city of Gardena.
Student Jacob Britton heard the gunshots.
I saw everybody running from the area, and I heard the gunshots at least two of them and then I heard the screams, said the student. Teachers ran out and told us to run to the closest classroom.
Police said the weapon was recovered, and the student was arrested shortly before noon in a classroom that was filled with students and one teacher.
The shooting was reported at 10:30 a.m. at the campus at 1301 W. 182nd St., according to the Los Angeles Fire Department. Gardena police Lt. Steve Prendergast said a teacher called 911 to report the shooting.
At about noon, officers began escorting groups of students out of the building.
An information hotline for parents is available by calling 310-354-3400. Parents were advised to text 90247 to the number 888777, and they would receive a text message back providing them with information about when they could pick up their children.
Gardena High School has at least 2,600 students.