Officers Hone Their Riot-Reaction Skills : Training: A two-day course is designed to prepare police to respond quickly to civil disturbances.

The victim lies broken and helpless on the asphalt roadway, like the truck driver whose battered image became all too familiar to Los Angeles and the world.

Abruptly, though, three black-and-white police cars, sirens wailing, roar alongside the prone figure. Brakes screech and officers alight swiftly, hauling the limp victim into a sedan as their partners draw pistols and provide cover. Within seconds the lawmen have sped off, the casualty--actually a dummy--whisked away to safety.

“This is a Reginald Denny situation here,” explains Los Angeles Police Lt. Michael Hillmann, referring to the beating at the outset of last April’s riots that emerged as a videotaped symbol of police inaction. “To have an injured individual laying out there without being rendered help is unacceptable.”

Officers re-enacted the episode--with the far different conclusion--during a new LAPD course in “unusual occurrence” preparation, better known as riot training. Launched in November, it is both an exercise and a high-profile, not-so-thinly veiled warning to would-be rioters as the federal trial begins for four policemen accused of brutalizing Rodney G. King.

“We will respond aggressively to overwhelm any individuals who are causing the disorder and put a stop to it,” vowed Hillmann, who oversees the exercises in Dodger Stadium parking lots and nearby grounds.

But even beyond broadcasting a message of police readiness to the streets, authorities are clearly attempting to accomplish something broader: obliteration of the riot-etched image of a vacillating, dilatory department and renewal of a sense of initiative and confidence in a dispirited force.

“We try and reinforce the idea to be pro-active, to have a can-do attitude,” said Sgt. Grady Dublin, a burly 25-year-veteran who is among the trainers wearing gray camouflage khakis, combat boots and black T-shirts emblazoned with green “civil disorder” logos.

In the view of commanders, those intent on crime should now face a transformed LAPD: mobile, quick to react and poised for any eventuality.

“When you have 200 to 300 officers sitting around a command post and everyone is wringing their hands, that’s unacceptable,” Dublin says at day’s end, recounting one of the most infamous police management failures of the riots.

At the core of the two-day riot-training regimen are a series of specially designed exercises, from rescuing victims (the Denny scenario) to dispersing hostile crowds to the use of tear gas. All of the city’s more than 7,000 officers are scheduled to participate, 100 at a time.

It remains to be seen, of course, whether this show of military-style preparedness and the accompanying publicity will avert, or limit, future disturbances. Mistrust of police runs deep in riot-ravaged communities, and, as the city learned last spring, civil unrest, once sparked, can spread out of control as quickly as a tenement fire.