Police say the two 15-year-old girls were found dead Friday morning at Independence High School in the Phoenix suburb of Glendale.
Authorities didn't know what led to the shooting but say they're not looking for anybody else. A gun was found near the bodies.
Hundreds of concerned parents have been waiting outside stores near the school. School district Superintendent Brian Capistran told reporters that parents will be bused to campus to meet their children.
He says families then will be taken off campus by bus. Students may also ride their normal buses home.