This is reconstructed from two eyewitnesses in different positions and mostly corresponds to what I could hear from a nearby location without a clear view of the area:

At 5:50pm amid multiple cars and a cruising crowd, 2 shots were fired that sounded like they may have come from a handgun. At that point one witness saw people rushing southward on Buffum away from the Meinecke intersection except for individuals by cars halfway up the block who seemed to be responding to an attack from the north toward the intersection. One such individual was observed with a .40 caliber S&W handgun; this was a young black male with a dark hoody sweatshirt and some kind of metallic stitching or print on the jacket with dark blue/black jeans and white sneakers. He was facing north up Buffum towards the Meinecke intersection, scanning for targets. His weapon was black and appeared new and in good condition.

3-4 shots from a higher caliber (or perhaps simply louder) weapon were then directed down toward this individual and others, so it is possible that the group on foot initiated the first round of gunfire. At least some of the second round of shots were observed to come from a Tahoe that had come up Meinecke, made a u-turn on the intersection with Buffum, and a passenger was firing an assault rifle (thought to be an AR-15) out the window. Eyewitnesses who saw this vehicle thought two shots came from it as it turned and 3 more as it turned again. The initial shots were definitely quieter and presumably came from a smaller size weapon than the later shots.