Several residents had to be rescued, but it wasn't until hours after fire started that one person was discovered dead inside the building.
Authorities said surveillance video captured the incident and text messages between Chase Lackard and his mother allegedly showed her coordinating where and when to pick him up after the shooting.
Mount Vernon's deputy commissioner of public safety was arrested for allegedly being the getaway driver for her son, who was wanted in a shooting in the Bronx.
While it remains unclear whether Brandon Garcia knew the teenagers who were shot, his family said he was not involved in any gang activity.