Reports say it happened in front of the Vogue, an old neighborhood movie house turned (lo, these many years) into a nightclub, just after 2:30 this morning. Victim is in hospital with "non-life-threatening" injuries. Meanwhile, the shooter is said to have run east and IMPD admits to having arrested at least one guy a couple blocks east of the scene. They aren't calling him the perp yet.
This sort of thing does occur, though at far greater intervals than the easily-panicked would have you think. Flip side, robberies (and attacks, until now) have not been happening.
Past that, there is not enough information to speculate -- despite at least one ill-informed comment at the link. Choirboy menaced by a miscreant? Horseplay gone wrong? Thug-on-thug violence? Objection to wearing paisley with bold stripes? Perhaps we'll know more tomorrow.
5 weeks ago