The gunman gained entry into a residential facility by posing as a police officer, dressed all in black with a vest emblazoned with “police” and a star badge around his neck, according to photos taken from surveillance video.According to the preliminary investigation, once he was inside “and after a brief conversation,” the gunman “produced a handgun and discharged it multiple times, striking both victims,” police said.The gunman claimed he was an officer serving a warrant on one of the juveniles housed at the privately owned facility, NBC Washington reported.“He was absolutely trying, specifically targeting that individual,” Haines said.Police are asking the public to help identify the gunman or the vehicle he used to escape."