Perhaps the competition was at its best with the "30-round Diminishing Light Modern Stress Course," a trial by fire for any law enforcement officer.

Computer-controlled, dim when well lit, the shooting range for the first regional patrol officers' competition was where nerves and mettle, method and even manners, were tested yesterday.

The object was to hit the target 30 times, no easy thing when it kept moving downfield and into an increasingly darkened room. And then, there were the sirens and yells, which were supposed to contribute to the stress.

"No one has blown anyone right out of the water," said Lt. Joe Winter, the firearms commander for the U.S. Park Police. "In this type of course, going into it cold, they're all doing relatively well."

The shooting range was inside the Anacostia operations facilities of the U.S. Park Service, which conceived of the Patrol Officer Competition and co-hosted it yesterday with the Metropolitan Washington Council of Governments. In the surrounding fields there were the defensive driving course, the traffic stop competition and the room search.

In each, the 60 or so representatives from 15 local law enforcement agencies received scores for their performances. The testing, at least in the case of the traffic stop, was so thorough that the grade sheet was three pages long.

Brent Knowles, a two-year member of the Loudoun County Sheriff's Department, did well in the simulated traffic stop, according to the judges, who did not want individual scores released.

"Does the officer have gun hand free?" the questionnaire asked. Knowles not only had it free, he also kept it on the gun until the "suspect," Park Police Officer James Tsu, was no longer a threat.

"Does suspect face officer while he goes into the prone position?" In this case, Knowles did not subject Tsu, who was supposed to be driving a stolen car, to the prone position. Tsu had not been so lucky with the contingent from the Marines, which went by the book, even as far as putting a knee on his neck.

Knowles found two toy guns, one carried by Tsu and a second hidden behind the driver's sun visor. "He was thorough," Tsu said. "He kept me off balance."

For Knowles, who already had survived the driving course, there were lessons to be gained. "It already made me think about the corners of my car," he said. "I think I'm going to learn something from this."

The idea for the competition originated with Park Police Maj. Andre' R. Jordan, who wanted a contest solely for patrol officers. Although equestrian and motorcycle units compete, no such gathering existed for patrol officers. A year and a half ago, Lt. William J. Ruth, also of the Park Police, began working in earnest on the project.

A committee was formed, and after countless meetings and consultations with other law enforcement groups, the four contests were developed.

"What we wanted to do is make something realistic, something you'd run into day and night, and be able to handle yourself," Ruth said. "The little things you have to do . . . . You have to go by the numbers for your own safety."