HIGHLAND PARK, Ill. (AP) — FBI agents peeked into trash cans and under picnic blankets Tuesday as they searched for more evidence at the site where a gunman fired on an Independence Day parade from a suburban Chicago rooftop in an attack that killed at least six people.

The assailant's shots were initially mistaken for fireworks before hundreds of panicked revelers fled in terror in Highland Park, a close-knit community on the shores of Lake Michigan that has long drawn the rich and sometimes famous.

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A day later, baby strollers, lawn chairs and other items left behind by panicked parade goers remained inside a wide police perimeter. Outside the police tape, some residents drove up to collect blankets and chairs they abandoned.

Authorities detained a suspect Monday evening in a traffic stop that led to a brief chase. Police initially described the man as a person of interest, but a spokesman for the Lake County Major Crime Task Force said Tuesday that he is now considered a suspect.

Charges were expected to be announced soon, according to a spokeswoman for the Lake County state's attorney, Sara Avalos.

Authorities offered no motive for the attack.

The July 4 shooting was just the latest to shatter the rituals of American life. Schools, churches, grocery stores and now community parades have all become killing grounds in recent months. This time, the bloodshed came as the nation tried to find cause to celebrate its founding and the bonds that still hold it together.

"It definitely hits a lot harder when it's not only your hometown but it's also right in front of you," resident Ron Tuazon said as he and a friend returned to the parade route Monday evening to retrieve chairs, blankets and a child's bike that he and his family abandoned when the shooting began.

"It's commonplace now," Tuazon said. "We don't blink anymore. Until laws change, it's going to be more of the same."

The shooting occurred at a spot on the parade route where many residents had staked out prime viewing points early in the day for the annual celebration.

Among them was Nicolas Toledo, who was visiting his family in Illinois from Mexico. He was shot and died at the scene, his granddaughter, Xochil Toledo, told the Chicago Sun-Times. Also killed was Jacki Sundheim, a lifelong congregant and "beloved" staff member at nearby North Shore Congregation Israel, which announced her death on its website.

Dozens of fired bullets sent hundreds of parade-goers — some visibly bloodied — fleeing. They left a trail of abandoned items that showed everyday life suddenly, violently disrupted: a box of chocolate cookies spilled onto the grass; a child's Chicago Cubs cap; baby strollers, some bearing American flags.

"There's no safe place," said Highland Park resident Barbara Harte, 73, who had stayed away from the parade fearing a mass shooting, but later ventured from her home.

Highland Park Police Chief Lou Jogmen said a police officer pulled over Robert E. Crimo III about 5 miles (8 kilometers) north of the shooting scene, several hours after police released the man's photo and warned that he was likely armed and dangerous.

Authorities initially said Crimo, whose father once ran for mayor of Highland Park, was 22, but an FBI bulletin and Crimo's social media said he was 21.

Lake County Coroner Jennifer Banek said the five people killed at the parade were adults, but didn't have information on the sixth.

Police have not released details about the victims, but Toledo's granddaughter told the Sun-Times that Toledo had spent most of his life in Morelos, Mexico. Xochil Toledo said she remembers looking over at her grandfather, who was in his late 70s, as a band passed them.

"He was so happy," she said. "Happy to be living in the moment."

Xochil Toledo said her father tried to shield her grandfather and was shot in the arm; her boyfriend also was shot in the back and taken by someone to nearby hospital because they weren't sure there would be enough ambulances for all the victims.

Roberto Velasco, Mexico's director for North American affairs, said on Twitter that two Mexicans were also wounded.

Sundheim had spent decades on the staff at North Shore Congregation Israel, early on teaching at the congregation's preschool and later serving as Events and B'nei Mitzvah Coordinator, "all of this with tireless dedication," the congregation said in its statement announcing her death.

"Jacki's work, kindness and warmth touched us all," the statement said.

NorthShore University Health Center received 26 patients after the attack. All but one had gunshot wounds, said Dr. Brigham Temple, medical director of emergency preparedness. Their ages ranged from 8 to 85, and Temple estimated that four or five were children.

"It is devastating that a celebration of America was ripped apart by our uniquely American plague," Illinois Gov. J.B. Pritzker said at a news conference.

"While we celebrate the Fourth of July just once a year, mass shootings have become a weekly — yes, weekly — American tradition."

Since the start of the year, there have been 15 shootings where four or more people have been killed, including the Highland Park one, according to The Associated Press/USA TODAY/Northeastern University mass killing database.

Highland Park Police Commander Chris O'Neill said the gunman apparently used a "high-powered rifle" to fire from a spot atop a commercial building where he was "very difficult to see." He said the rifle was recovered at the scene. Police also found a ladder attached to the building.

The task force spokesman, Christopher Covelli, said that Crimo legally purchased the gun in Illinois within the past year.

Crimo, who goes by the name Bobby, was an aspiring rapper with the stage name Awake the Rapper, posting on social media dozens videos and songs, some ominous and violent.

In one animated video since taken down by YouTube, Crimo raps about armies "walking in darkness" as a drawing appears of a man pointing a rifle, a body on the ground and another figure with hands up in the distance.

Crimo's father, Bob, a longtime deli owner, ran unsuccessfully for mayor of Highland Park in 2019, calling himself "a person for the people."

The community of about 30,000 on Chicago's north shore has mansions and sprawling lakeside estates and was once home to NBA legend Michael Jordan.

Gina Troiani and her 5-year-old son were lined up with his daycare class ready to walk onto the parade route when she heard a loud sound that she believed was fireworks — until she heard people yell about a shooter.

"We just start running in the opposite direction," she told The Associated Press. "There were people that got separated from their families, looking for them. Others just dropped their wagons, grabbed their kids and started running."

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Foody contributed from Chicago. Associated Press writers Martha Irvine and Mike Householder in Highland Park; Mike Balsamo and Bernard Condon in New York; David Koenig in Dallas; Jeff Martin in Woodstock, Georgia; Fabiola Sánchez in Monterrey, Mexico; and Jim Mustian in New Orleans contributed reporting.