Are you thinking about the MOVE standoff/shootout in Philly in 1985?
http://philadelphianeighborhoods.com/2010/06/28/west-philadelphia-25-years-later-move-on-the-move/
Great catch! Yes, that is what I was referring to.
I had forgotten that the Philadelphia PD bombed them, though. Thought it was a bomb factory that blew up.