Incorrect. LA County Fire is the ALS provider. Schaefer ambulance currently has the BLS ambulance contract for that area.
AMR only has a portion of the BLS ambulance contract for LA county 911. McCormick, Scahefer and Care all have contracts in different areas of the county. NONE of them provide ALS service to the 911 system. Medics for these companies mostly function at the BLS level when on 911 calls (there are occasions when they get to do ALS procedures but its usually with permission from the on scene fire medics). They only really are ALS when doing IFTs...or if its Armageddon and there are no medics to respond to a call...but that is super rare.
Why is it like this? Because LA county operates a fire-based EMS model.