THE GUARDIAN ANGELS, a newly renowned youth street patrol organization, arrived in Washington last week, prompting some uneasiness and cynicism. Mayor Barry and Police Chief Turner bristled at not having been informed that the Angels were coming to town. Other city officials expressed anxiety that the Angels would encourage dangerous vigilante action if not actually take part in it. The Angels are a group of mostly young men who train themselves in the martial arts, dress in red berets and walk through the toughest parts of town seeking to stop the muggings, fights and purse-snatching that have become a commonplace of American life.

Some reaction to the Angels here and in other big cities would lead to the conclusion that the Angels want to replace the local police or start fights on every corner where there isn't already a fight in progress. But the Angels so far appear to be essentially harmless but loud-talking youngsters with good intentions. They are certainly not large in numbers or in the impact they have on crime in any city.

The publicity that comes to the Angels seems disproportionate to their importance. It overstates what they do, which is to deter crime by walking around and looking tough. But the publicity grows out of the nationwide frustration over crime. While police and city officials do not appreciate the attention the Angels might bring to their own failed efforts to control crime, the people who live in fear of crime appreciate any help and protection they can get. Of course, the Angels did not exactly reassure local leaders by making a splash on TV or by upbraiding the mayor for not welcoming them -- as they did here, saying: "We're not here for Mayor Barry or the police chief, we're here for the people."

Despite the cold official reception, the Angels were warmly greated by Washingtonians when they set up a registration table on the Capitol steps. Over 50 people signed up to be part of the Washington branch. The Angels' experience here seems a reflection of what has happened to them as they have gone across the country in the last few weeks, setting up bureaus in 17 cities.

Whether the Angels actually fight crime is not so important as the feeling they communicate of understanding the terror of street crime and wanting to stop it. In fact, they have only about 100 members outside the New York City, and even in New York -- where they have 700 members -- they have made only 100 citizens arrests in more than two years. Still, their presence in some situations seems to reassure people and to give the bad guy an extra reason to worry. That's not all bad.