DOUGLAS, Ariz (Reuters) - Walls get tagged with graffiti. Cars get shot up in drive-by shootings. Youngsters flash gang signs and battle with bricks, sticks, bats and pipes in the local park over turf.

A cinderblock wall sprayed with graffiti marking the territory of the Rollin 30's Crips from south central Los Angeles, is seen in Sierra Vista, Arizona in this July 1, 2008 file photo. REUTERS/Chris Burdick-Sierra Vista Police Dept/Handout

Once a sleepy smelter town on the Mexico border, Douglas is one of several cities in southern Arizona that are being transformed into urban battlefields as warring street gangs muscle in from southern California, police say.

A sun-baked backwater of broad streets and bungalows set in vast, high desert ranchland, Douglas is now a patchwork of territories held by the East Side Torrance and the South Side Harbor City, both Los Angeles-area street gangs, as well as lesser home-grown gangs.

A few miles up the road in nearby Sierra Vista, a boomtown in the shadow of the looming Huachuca Mountains, police say various factions of the Crips, also from Los Angeles, are warring for control of new streets, malls and subdivisions with the Bloodlines, a local gang.

The newcomers, many tattooed and wearing colors, are part of a scramble by street gangs to make money from tons of illegal drugs pouring over the border to Arizona from Mexico each month, along with tens of thousands of fee-paying illegal immigrants.

“For the gangs, it’s always about the money,” said Detective Tony Morales of the Arizona Department of Public Safety’s State Gang Task Force, whose members patrol the streets of Douglas, population 17,000, in flak jackets.

“Who has money? The people that move drugs have money, and the people that move illegal aliens have the money, and they end up in our corridor here.”

SMUGGLING PROFITS

Smuggling is big business in southern Arizona, where last year the Border Patrol seized 440 tons of marijuana in a furiously trafficked corridor south of Tucson and arrested more than 370,000 illegal immigrants.

Police say the gangs, which offer easy money and a sense of belonging to youngsters, are recruiting teens and sometimes children as young as eight, as foot soldiers in the trade worth billions of dollars a year.

Gang members steal vehicles stateside and drive to Mexico where they collect marijuana loads and groups of fee-paying illegal immigrants from Mexican smugglers, as well as consignments of prescription drugs.

Crossing back north over remote stretches of the desert border, they spirit their loads up to the Interstate 10 freeway and on to Tucson, Phoenix and the gang wracked sprawl of southern California several hours drive to the west.

In fast growing Sierra Vista, population 42,000, police say the gangs are also carving up the city’s neighborhoods among themselves, and peddling drugs including crack cocaine and methamphetamine to the new residents.

The gangs there include the Maryvale Crips -- a Phoenix affiliate of the notorious Los Angeles street gang -- and the so-called 520 Crips, who take their name from the area code for Tucson and southern Arizona.

“The amount of money being made is unlimited,” said Arturo Acosta, a Border Patrol agent assigned to a multi-agency gang taskforce that has been meeting since January to tackle the problem.

“Right now there is no end in sight, they’ll just keep on coming.”

DRIVE-BY SHOOTINGS

The gangsters’ arrival has been accompanied by increasingly brazen shootings and aggravated assaults as the proliferating street gangs scrabble for territory.

In Sierra Vista, it began with a drive by attack on a home last year, and spiraled to a spate of revenge shootings, resulting in one death and several woundings. as the violence gathered pace.

“It’s getting worse, it’s getting more public. It’s not one-on-one anymore ... it’s more in your face,” said Lori Burdick, a detective with the Cochise County Sheriff’s Office, who tracks the gangs.

To add to the misery, police say more California gangsters are pouring into the corridor each month, many fleeing the “three strike” law that puts repeat offenders behind bars for life on a third conviction.

Police have spotted members of the Fresno Bulldogs, from Fresno, California, in Sierra Vista, and affiliates of the Mara Salvatrucha, a Salvadoran gang originally out of Los Angeles, in Elfrida, a remote farming town nearby.

Then two weeks ago, graffiti for the Rollin 30’s Crips, a gang from South Central Los Angeles, tagged a cinder-block wall in the city.

For worried city authorities in the corner of Arizona better known for its county fairs and rodeos, the spiraling problem marks a shocking loss of innocence.

“When I was young, the worst trouble we ever got into was for serenading our girlfriends late at night,” said Douglas mayor Michael Gomez, a retired dentist who took office last month.