Maricopa County Sheriff Joe Arpaio's office said Wednesday that the patrols were launched earlier this week at 59 schools in unincorporated areas and communities that pay his agency for police services.
Arpaio hopes to have as many as 400 posse volunteers and another 100 volunteers known as reserve deputies take part in the patrols.
The plan from the sheriff known for immigration enforcement and housing jail inmates in canvas tents has led some longtime critics to say Arpaio's latest effort is meant to grab headlines and won't be sustained over the long term.
"Why would people complain about my posse being in front of schools to act as prevention?" Arpaio asked, noting that he wants the patrols to last throughout the remainder of the school year.
The sheriff said school shootings in Connecticut and elsewhere and last month's arrest of an Arizona student accused of planning an attack at her high school led to his decision to launch the patrols.
The volunteers, dressed in uniforms and driving patrol vehicles, won't go onto school grounds unless they spot danger and won't sit in stationary spots. Instead, they'll patrol several schools as part of their driving routes.
"We are paying him to have certified deputies here, not to bring a circus and not to use our town as a political platform," Sanchez said.
He predicted the volunteer patrols would disappear once media attention had faded.
Distrust of Arpaio in Guadalupe runs deep after the sheriff's deputies poured into the town during one of his first trademark immigration sweeps in April 2008.
During the crackdowns, deputies surge into an area of a city—in some cases, heavily Latino areas—to seek out traffic violators and arrest other offenders over several days.
Arpaio announced his plans Wednesday on the grounds of an elementary school, saying he wants the patrols publicized.
"I want everyone to know about it for the deterrence effect," he said.
The announcement came on the same day that the top Democrat in the Arizona House put forth a proposal to triple funding for school resource officers, add money for mental health treatment and require background checks on all buyers at gun shows.
Arpaio said no taxpayer money would be spent on the patrols and volunteers will be supervised by radio or phone by deputies.
Joselyn Wells, the mother of three children at a school in suburban Anthem, where Arpaio's posse members have begun patrolling, said she was excited to hear about the initiative.
"A lot of people sit around and watch these things happen, watch key signs and no one wants to do anything about it," she said. "Nobody wants conflict, nobody wants to be out in the limelight. And he doesn't care. He wants to do the right thing."
Arpaio has relied heavily on his posse, which consist of about 3,000 unpaid civilians, including action-film star Steven Seagal.
They assist deputies in duties such as providing free police protection at malls during the holidays, directing traffic at wreck scenes and transporting to jail the people who are arrested in immigration patrols. One group of posse members conducted an examination into the authenticity of President Barack Obama's birth certificate.
Members wear uniforms and can get authorized to carry a gun after training, though only 400 can actually carry guns. They can make arrests only at the direction of a deputy sheriff. Posse operations generally don't receive taxpayer money and instead are funded through contributions and dues paid by posse members.
The reserve deputies who will join posse members in the school patrols have all the training and powers of a regular law enforcement officer but aren't paid for their police work.
Monica Allread, spokeswoman for the Tempe Elementary School District, which includes an elementary school in Guadalupe, shied away from commenting on Arpaio's new plan. But she said the district aims to improve safety at its schools.
"Anyone who wants to help us keep the kids safe, that's a good thing to us," she said.