My guess is that there was an accidental discharge (police? bikers?) and the fusillade started.
The answers may be facts from these questions:
1. Were all expended cartridge cases on the scene collected?
2. By whom?
3. Have they been securely retained?
4. Where were they located when collected?
5. What calibers were they?
6. How many?
7. Do they match the wounds of the dead and wounded?
The above would normally be designated as evidence.
If so, and it was a biker, the cops would have a get out of jail free card - cops initiated or no reason for all the "issues" with the case.
“My guess is that there was an accidental discharge (police? bikers?) and the fusillade started.”
Statements from bikers at the scene say it was more like an execution shot by the Bandidos.