Sheriff Joe Arpaio traded angry words and accusations with Mesa officials Thursday after 60 deputies and posse members armed with search warrants stormed City Hall and the public library in the middle of the night in a hunt for illegal workers.

"I believe the safety of our citizens was gravely compromised" when Maricopa County sheriff's deputies in "battle gear" swept into city buildings about 2 a.m. while cleaning crews were at work, Mesa Mayor Scott Smith told reporters. "I believe we had set the scene where bad things could have happened."

Arpaio defended his tactics, claiming the raid came only after a former city employee called the sheriff's illegal-immigration hotline to report that a cleaning company under contract with the city was hiring illegal immigrants.

Arpaio said the informant had tipped off a Mesa police lieutenant and said the lieutenant brushed off the request, saying it was a problem for the cleaning company.

But a city spokeswoman late Thursday said police Lt. Wade Pew and city staff met with the cleaning company, Management Cleaning Controls, on May 21 after he received the information.

A follow-up e-mail sent June 4 by facilities maintenance director Dennis Ray to cleaning company officials reiterated the city's concerns over "several security issues that have recently been brought to our attention," and included a section of the city's contract requiring that contractors ensure all workers are legal.

Predawn raid

Arpaio said the raid was set up after a sheriff's undercover detective infiltrated the cleaning business, claiming to be an undocumented immigrant, and was schooled by a manager in how to obtain false identification that would get him past federal identification verification software.

About 30 deputies and 30 volunteer posse members in bulletproof vests and carrying semi-automatic weapons prepared for the operation in Pioneer Park across from the Mormon Temple shortly after midnight.

The deputies, carrying 25 arrest warrants, headed for the library and City Hall, an eight-story building that houses several municipal departments as well as the mayor's and council members' offices.

Deputies fanned out and arrested three people; 13 others, including a manager at Management Cleaning Controls, were arrested at residences later that morning, Arpaio said. Ten were arrested on suspicion of identity theft and six for potentially being in the country illegally.

The 16 arrested included six people who were not named in the warrants. Arpaio said they are still looking for 15 more company employees.

Smith said that most of the janitorial workers at the public buildings were either U.S. citizens or in the country legally and that they were terrified by the size and firepower of the sheriff's force.

Deputies returned to Mesa about 8 a.m. seeking records related to contractors at the city's Municipal Security Badging Office.

Smith said if the Sheriff's Office wanted information about contractors and employees, it could have submitted a public-records request and easily obtained the information.

Smith said at a news conference that a Mesa officer came across the deputies about 12:30 a.m. as they staged at the park "dressed in battle gear, with canines and semi-automatic weapons."

When the officer recognized the men as sheriff's deputies, Smith said, "He was told they were not allowed to tell him what their purpose was. . . . He never got any information. Approximately an hour later, the city was told that they were there for K-9 training."

Because of that, Smith said, there was enormous potential for death or injury had Mesa police responded to a 911 call from someone who had seen armed men gathering in the park.

Smith, who appeared distraught as he spoke with reporters, said he also took great offense that City Hall was targeted.

"The citizens of Mesa, Arizona, this is their City Hall. (It) was, in my belief, violated by another government agency. I don't believe that's proper . . . and I believe that also crosses the line as to what law enforcement should do," he said.

Questions denied

Arpaio denied questions about whether the raid was politically motivated or that it was timed to deflect attention from a videotape that surfaced Wednesday depicting the brutal death of an inmate at a county jail, which his office runs. The inmate's family has filed intent to sue the county.

Joining Arpaio in an afternoon press conference, Maricopa County Attorney Andrew Thomas said the cleaning company had been under investigation for months. When asked why Mesa police could not handle the case, Arpaio said, "It's my jurisdiction, too. You seem to forget."

Then he suggested that there was something in the Mesa police "culture" that "they do not want to enforce the immigration laws."

Smith denied that, saying Mesa police cooperate routinely with other law agencies. Smith said he's not trying to pick a fight with Arpaio and hopes to meet with the sheriff to talk about how the city and county can cooperate in the future.

History of discord

Thursday's raid is the latest in several immigration-related incidents this year involving the Sheriff's Office and the Valley's second-largest city.

In April, after Arpaio had begun conducting his controversial crime-suppression sweeps in the Valley, Mesa Police Chief George Gasc�n and the head of one of Mesa's two police unions made a request. They asked Arpaio for at least two days' notice before conducting sweeps in the city, citing potential risks to officers and the public. Arpaio responded by calling Mesa police uncooperative.

In early July, Smith and Gasc�n announced a new immigration-enforcement policy in the city, one in which every person arrested is asked about immigration status. Arrested people suspected of being illegal immigrants are to be referred to federal authorities.

But Mesa's policy specifies that police will not arrest everyone they think might be an illegal immigrant. People pulled over for minor traffic violations, for example, would not be arrested even if they admit they're here illegally. Instead, their information would be turned over to federal officials.

Two weeks after that policy was announced, Arpaio was back in Mesa, arresting about 40 people, including 26 suspected of being undocumented immigrants.

A Mesa landscaping company was raided Aug. 27, and three dozen people suspected of being in the country illegally were taken away. It was later learned the city contracted with that firm to landscape its parks.