WILLOWBROOK, Ill. (AP) — At least 23 people were shot, one fatally, early Sunday during a gathering in a suburban Chicago parking lot that drew hundreds of people to celebrate Juneteenth, authorities said.

TV news video showed the strip mall lot in Willowbrook filled with debris and police tape, about 20 miles (32.1 kilometers) southwest of Chicago. The DuPage County Sheriff's Office described it as a “peaceful gathering” to celebrate Juneteenth that suddenly turned violent as a number of people fired multiple shots into the crowd.

“We know of 22 victims injured and one victim killed by gunfire. Several other victims were also injured while attempting to flee the area,” the sheriff's office said in a statement. Authorities didn't immediately release the conditions of those injured.

A motive for the attack wasn’t immediately known, and no one was arrested by early evening. Sheriff's spokesman Robert Carroll said authorities were interviewing “persons of interest” in the shooting, the Daily Herald reported.

The Willowbrook shooting was just one in a string of weekend shootings across the U.S. that killed at least six people, including a Pennsylvania state trooper, and injured dozens. The shootings in Illinois, Pennsylvania, Washington state, Missouri and Maryland follow a surge in U.S. homicides over the past several years.

Police were at the strip mall before the shooting to monitor the gathering, but were called away because of a nearby fight, the sheriff's office said. “They heard gunshots and immediately returned to the scene," the sheriff's office said.

"We transported numerous victims from the scene. Others just walked into area hospitals," said Eric Swanson, deputy chief at the sheriff’s office.

Rick Wagner, who lives nearby, said there were at least 300 people in the lot by 10:30 p.m. “We’ve had multiple conversations with police" about large groups meeting there, Wagner told the Daily Herald.

A witness, Markeshia Avery, said it was a Juneteenth celebration. Monday is the federal holiday commemorating the day in 1865 when enslaved people in Galveston, Texas, learned they had been freed — two years after the Emancipation Proclamation.

"We just started hearing shooting, so we dropped down until they stopped,” Avery told WLS-TV.

Another witness, Craig Lotcie, said: “Everybody ran, and it was chaos.”

Illinois Gov. JB Pritzker said in a statement that he was monitoring the investigation.

“Gathering for a holiday gathering should be a joyful occasion, not a time where gunfire erupts and families are forced to run for safety,” Pritzker said.

The White House released a statement Sunday afternoon, saying that the “President and First Lady are thinking of those killed and injured in the shooting in Illinois last night. We have reached out to offer assistance to state and local leaders in the wake of this tragedy at a community Juneteenth celebration.”