Don't know yet, but he was wanted:
"OAKLAND, Calif. -- Three Oakland police officers were killed, another gravely wounded and a suspect was slain in a gun battle with a SWAT team Saturday in two related shootings that have rocked the community, authorities said. . At an emotional Saturday evening press conference, Acting Oakland Police Chief Howard Jordan confirmed the deaths."
-snip-
"The officers killed were identified by Jordan as Ervin Romans, 42, and Daniel Saki, 35. The gunman was identified as Lovell Mixon, 27, Oakland. He was wanted for a parole violation, Jordan said."
I know this is second guessing but why was he out in the first place, I wonder?!