That man, Christopher Thomas, remained in UPMC Mercy hospital on Wednesday.
Police continue to investigate the incident about 2:20 a.m. Tuesday. That's when police said Thomas and another Pittsburgh man, 31-year-old David Calhoun, fired a shot through an apartment door and forced their way into a unit where a 19-year-old man and a 17-year-old female lived.
Investigators said the 19-year-old grabbed a shotgun and killed Calhoun while wounding Thomas.
Police have yet to identify the resident gunman or say whether he'll be charged, too.
Thomas, the wounded suspect, has also been charged with illegally carrying a firearm, aggravated assault and conspiracy.