LOS ANGELES (AP) _ A gang of about 150 well-organized, ''streetwise'' hoodlums has netted millions of dollars by smashing and shooting its way into elegant jewelry stores in six Western states, authorities say.

The bandits, age 13 to the late 20s with possible ties to Los Angeles street gangs and apparently directed by adults, rent cars for robberies using stolen credit cards and leave on the first flight out, police say.

''They storm a place,'' said Los Angeles robbery Detective Robert Johansen. ''They walk in ... with a sledgehammer and have everyone lay on the floor away from the (alarm) button.''

Teams consist of a driver, a gunman, a smasher and a scooper, Johansen said. The smasher uses a tire iron, hammer or baseball bat to break the glass cases and the scooper takes the jewels, he said.

Police estimate the gang has 150 members who have pulled about 50 robberies this year in California, Arizona, Utah, Washington, Oregon and Nevada.

''These guys were very streetwise,'' said Sgt. Dee Rowland, a detective in Murray, Utah, a suburb of Salt Lake City. ''When we arrested them, they gave us nothing. They wouldn't even admit they were at the hotel we watched them walk from.''

Three men captured last year after a $200,000 jewelry holdup at a suburban department store are serving sentences in Utah State Prison, he said. A fourth, Ronald Prince, vanished last year after a magistrate released him because his jail paperwork was not processed after a holiday weekend.

Prince, 19, surfaced in Bakersfield, where he and four alleged accomplices face a preliminary hearing today on robbery charges stemming from a Nov. 4 department store holdup that netted $180,000 in jewelry.

In both cases, police recovered most of the jewels and precious metals, but investigators suspect most of the goods that are not recovered flow to masterminds who are senior in years and can fence them.

''They are getting substantial amounts - from $150,000 to as high as $500,000,'' said Bakersfield detective Sgt. Floyd Bertrand. ''When they hit, they are hitting the nicer places.''

''I don't think these kids are smart enough to get rid of a humongous amount of jewelry,'' Johansen said. ''We would love to know the next level of the organization.''

The smash-and-grab robbery technique isn't new, but the age of the robbers is going down and the frequency of the attacks, apparently by one gang, has increased to the point where jewelers across the West have been alerted.

''There seem to be two groups that are related. There is a 13-to-17-year age group and then a 20-to-27-year category,'' Johansen said. ''We are assuming the younger part of the group is being taught, being given an opportunity to learn.''

Suspects arrested in other states have come from south-central Los Angeles, supporting a theory that the group is tied to the city's street gangs, said Johansen, who investigates robberies in the West San Fernando Valley, where the most recent - and violent - holdup occurred.

Credit manager Ron Flury, 48, of Sylmar, was grazed on the left arm by a bullet Tuesday as he tried to escape out a rear door of a Reseda jewelry store.

''This was the first time anyone has been wounded in these robberies,'' said Johansen. ''Normally they just fire a warning shot.''

''There have been gangs doing this (smash-and-grab) for seven or eight years,'' said James White, president of the New York-based Jewelry Security Alliance, a company that advises store managers on crime prevention techniques.

''The ages are going down because they're teaching their kid brothers,'' he said. ''There is not really much that can be done to prevent armed robbery. In a retail store, you invite the public in. Once they pull a gun, the ball game is over. You obey because you want to prevent violence.''