Looks like the gunman who killed a bartender at Greenwich Village pizzeria DeMarco's and then two auxiliary police officers was not a former employee of the pizzeria, as was previously postulated. The New York Times:
A neighborhood resident, Tina Lourenco, told reporters that she had seen the gunman and recognized him as a former employee of the pizzeria.
But Dominick De Marco Jr., whose sister, Margaret Mieles, is a part owner of the pizza parlor, said Mr. Garvin was probably not a former employee, but instead a former customer.
Also from the Times, speculation on the motive:
Mr. Garvin, who moved to the Village from the Bronx about two weeks ago, had patronized the pizzeria occasionally and had been ejected several times for unruly behavior, a manager told the police. Investigators said that Mr. Garvin was the friend of a cook who had been fired by the pizzeria last fall, and for reasons that were unclear may have blamed Mr. Romero for the dismissal.
Greenwich Village Gunfight Leaves Four Dead [New York Times]
In Heart of Village, 4 Lives Intersect in a Chain of Violence [New York Times]