Kanei Avery was sentenced Thursday in the April shooting at Minaret Temple No. 174 in Chester.
The Delaware County Daily Times reports Avery will serve his time at a state correctional facility for youths. Now 18, he was 16 at the time of the shooting.
A hundred or more teens attended the party before shooting broke out, killing 18-year-old Robel Laboy and 19-year-old David Johnson. Seven other teens were wounded.
In October, Avery entered an open guilty plea to two counts of voluntary manslaughter. Delaware County prosecutors decided not to pursue murder charges, citing problems with evidence and witness cooperation.
Avery has apologized.
Information from: Delaware County Daily Times