Police originally said the fight was between two men. Officer Rachel McGuire says officers responded to the building in the city's Roxbury neighborhood at about 9:20 AM today.
She says during a physical altercation in a common area on an upper floor, one teen produced a gun that went off during the struggle.
Both teens were arrested but their names and exact ages have not been made public. Police have also recovered a gun. Commissioner William Evans said it's unclear what sparked the confrontation.
No additional information was immediately available.