A boy pleaded guilty on his 14th birthday Tuesday and a 12-year-old friend was convicted on charges of gunning down four schoolmates and a teacher in an ambush outside their school.

Mitchell Johnson admitted firing shots that killed the five last March. A lawyer for Andrew Golden, now 12, said the boy took part in the attack but was insane at the time and not mentally competent to understand Tuesday's hearing.Juvenile Court Judge Ralph Wilson Jr. rejected Golden's argument and found him guilty after a two-hour trial. A sentencing hearing for the two boys was to begin Tuesday afternoon.

Both boys were charged with five counts of murder and 10 counts of battery. Nine students and another teacher were injured in the March 24 ambush outside Westside Middle School. The victims were lured outdoors by a false fire alarm.

Wilson found that the boys were delinquent and can sentence them to a state youth center until they are 21 - though the state currently has no facility to hold them beyond age 18.