A 16-year-old boy who pleaded not guilty to juvenile murder and kidnapping charges in the fatal shootings of four people at an Ohio home has been charged with an additional delinquency count of attempted murder.

The Franklin County prosecutor's office said Wednesday a weapons violation charge was added.

Columbus police haven't publically provided a motive for the slayings, which were discovered Saturday.

Officers found a teenage girl injured outside the home, then discovered the four dead inside. The girl was treated at a hospital and released.

A spokeswoman for Prosecutor Ron O'Brien says a probable cause hearing is scheduled for Aug. 26 to determine if the teen should be tried as an adult.

The teen's attorney says he's reviewing evidence in the case.

Police are also seeking a second suspect.