By Kristen Johanson

PHILADELPHIA (CBS) – Authorities in Philadelphia are searching for a gunman involved in a drive-by shooting at a July 4th barbecue overnight that killed a teenager.

Police say it was just before midnight when officers arrived at a house hosting a barbecue in the backyard near 31st and Moore Street in Grays Ferry.

There, they found 16-year-old Asir Brown shot once in the back.

Brown was taken to Children's Hospital of Philadelphia and pronounced dead around 12:30 a.m.

Investigators are searching for a dark-colored vehicle, last headed north on 31st Street.

Anyone with information is asked to call police.