i immediately thought gunshots (based on sound and cadence). plus, the cops showing up made me figure someone was shooting. can't say I'm certain, though, so don't want to unnecessarily raise the alarm. my wife called the 14th and they investigated, based on numerous calls reporting the incident, and didn't find anything to warrant further investigation (i.e. a victim). but there were only two cops, and you'd prob have to look pretty hard to find casings in the snow. Either way -- gunshots or fireworks -- weird on snowy, 15 deg night!
I live on Mozart and heard a woman at the end of the block speaking with the cops. She said they looked outside after hearing the shots and saw 4 people running down Mozart towards Armitage. I think she was also describing a dark sedan driving by but didn't say it was speeding away or anything. Best bet, at this point, seems to be a gang-related shooting.