They had perfection: Glocks.
Seriously. Officers are not trained for that kind of combat. Glocks are NOT accurate at that range. Most police calibers are incapable of penetrating even the most basic vest, or armour, or, the ammunition is designed to expand, rather then penetrate.
The tactics of hiding behind a car become deadly when the bad guys are using rifle rounds capable of going through most everything in your average car. Cover in this case was non-existent. None of the weapons LAPD carried were capable of long range shooting, and, or, the officers were not capable of shooting at that range. It's the classic,
"You brought a pistol to a rifle/machine gun fight."
LAPD could have had a cheap rifle, like a Mosin Nagant, and, with proper ammo, and multiple positions, have been able to put the guys down quickly...