Update #2:
Binghamton Chief of Police will not confirm who the shooter was. Has asked for press not to circulate the name that's been going around. They haven't confirmed the identity of the killer, whether there were more shooters or the identity of all victims.

Update #1:
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From Multiple deaths feared in hostage-taking - Crime & courts- msnbc.com:

NBC's Pete Williams cited city and state officials as saying that as many 13 people might have been killed. But Williams cautioned that the information was very preliminary and may change by because police were still searching the building.

At least 41 people were in the American Civic Association building at the time of the shooting, The Binghamton Press & Sun Bulletin reported.  read more »