Contrast it with the North Hollywood Bank Shootout back in 1997. LAPD engaged early and didn’t quit.
The two perps were wrapped in heavy body armor and armed with AK-47s, an HK91 and a Bushmaster and handguns. They seriously outgunned the LAPD armed only with handguns and 12 gauges.
The robbers fired over a thousand rounds. 12 LAPD were hit. A SWAT team borrowed AR-15s from the B&B gun store and joined the battle. The running gunfight lasted almost an hour with the two criminals ending up dead.
LA is a _major_ population center.
The population of Ulvalde was 14,929 at the 2000 census, so it took a while for SWAT to arrive.