(Reuters) - Following a tip, a police SWAT team closed off the street, put a school on lock-down and then burst through the door of a shabby house where dozens of illegal immigrants were sheltering.

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The sheriff's deputies caught three men who took off running and arrested 24 people they suspected of being illegal immigrants recently arrived from Mexico.

"There were fire and police people going back and forth, the road closed off ... It was chaotic," said Virginia Mongold, who watched the operation unfold on Monday, the 56th such raid in the Phoenix valley this year.

Illegal immigration and border-related crime have residents like Mongold and their elected officials riled enough that Arizona passed the United States' toughest immigration law last month -- unleashing a fiery debate over crime, racial profiling and policing that reverberated far beyond the state's borders.

The law seeks to drive illegal immigrants from the desert state, the principal corridor for unauthorized migrants entering the country from Mexico, and a busy entry point for Mexican cartels smuggling drugs to a voracious U.S. market.

Arizona's Republican Governor Jan Brewer charges the federal government has failed in its duty to secure the border with Mexico, and says the state law is needed to curb violence and cut crime stemming from illegal immigration.

As examples of border-related crime, Brewer singled out "drop houses," where smugglers routinely beat migrants to get their money for guiding them over the rugged border, as well as kidnappings linked to the drug trade.

"There is no higher priority than protecting the citizens of Arizona," she said. "We cannot sacrifice our safety to the murderous greed of the drug cartels. We cannot stand idly by as drop houses, kidnappings and violence compromise our quality of life."

'MIGHT AS WELL BE MEXICO'

Almost two-thirds of Arizona voters and a majority of voters nationwide agree with her and support the law, polls show.

But as border crime grabs headlines in Arizona and beyond, U.S. government figures show that arrests on the Arizona-Mexico border have been falling since 2000. Violent and property crimes across the desert state have also declined, suggesting the picture is not as dire as Brewer claims.

In the sleepy street in Mesa where the police carried out their raid, residents grappled with their feelings about illegal immigration and border crime -- who is to blame for it and the best way to respond to it.

Mongold, a young mother who works at a small packaging store nearby, backs the law and blames Washington for failing to secure the border and stem illegal immigration from Mexico.

"I'm angry, I'm frustrated, I might as well be in Mexico there's so many of them," she said, referring to the 460,000 illegal immigrants estimated to live and work in the state, many as day laborers, landscapers, maids and restaurant cooks.

At the Mesa Preparatory Academy, which police locked down in the recent raid, principal Robert Wagner was more cautious about the threat posed by crime and immigration.

"It's somewhat disconcerting that it's going on in our neighborhood, but I don't believe that we are living or operating in fear," he said, choosing his words carefully.

"It is important to look at the facts before drawing a conclusion, and that's part of what we teach in this school." He declined to say whether he supported the law.

The Arizona state law catapulted immigration back to the forefront of U.S. politics and piled pressure on President Barack Obama to deliver on an election promise to Hispanics to overhaul immigration laws and create a path to citizenship for the country's estimated 10.8 million undocumented immigrants.

Obama said on Wednesday he wanted to begin work on immigration reform this year and that federal officials would mintor the new law in Arizona for civil rights implications.

Local law enforcement agencies in Arizona are divided over the measure, which requires state and local police to arrest those unable to provide proof they are in the country legally.

Writing in the Wall Street Journal, Sheriff Clarence Dupnik from the southern county of Pima, slammed it as "unnecessary ... a travesty, and most significantly ... unconstitutional."

The view echoed misgivings by Phoenix Police Chief Jack Harris who said that determining immigration status detracted from the main job of curbing violent and property crimes.

The tough law is set to come into effect in late July, but faces legal challenges from a variety of plaintiffs, including police officers, civil rights groups and city councils.

(Editing by Mary Milliken and Chris Wilson)