A garbage truck tipped from one alley onto parked cars in a lower alley.
http://blogs.townonline.com/brookline/2009/06/30/garbage-truck-crash-on-beacon-street/

The MassGIS import to OSM had this alley as Unnamed Road, although aligned to wrong building, but Google didn't have it at all.

I have aligned it per Yahoo imagery, and split the lower parking to a second way layer=-1, although it won't go under so -0.5 would be more accurate. Since news photo shows pavement, MassGIS tag surface=unpaved reset to surface=paved.