My 16 year old brother is in jail?

[Destiny]

Okay, he was arrested last night around midnight for assualt with a deadly weapon, on a $7,500 bond. He's in county jail. I wanna know how county can hold a 16 year old. Does anyone know why their holding him at county when he's a minor? Is it because he was charged with assualt with a deadly weapon? I don't know the weapon or anything else about it. They won't tell us. So, please any info would help