What's LAPD protocol when searching for potentially killed officers?

I'm writing a screenplay, and in the opening scene, the main character who is a LAPD officer is sent to a large, hard to navigate park (similar to central park) where shots have been fired and the police at the location are not communicating, and potentially dead.

When he and other officers arrive, they find the missing officers vehicle with nobody inside, spent shell casings about, and trails of blood leading in another direction. Upon further investigation they find the officer badly wounded, with his partner and assailant no where in sight.

So, my questions:

1. How many police would be dispatched to this situation? Would they be SWAT or regular police?

2. Knowing that officers lives may be in danger (both their own and the ones they're searching for) would they have to search the location? And if so, what would be their main priority? Find the officers? Find the assailant? If they found the officer, but no assailant, what to they do from there?

Any and all information on this kind of thing would be a huge help. Thanks!