A spray of bullets aimed at a funeral procession in a Chicago suburb left four men injured, one critically, according to police.

The shooting happened Saturday afternoon in the village of Oak Park as the line of vehicles traveled from Chicago to a cemetery in Des Plaines, about 20 miles northwest of the city, according to the Oak Park Police Department.

A white pickup truck pulled alongside one of the procession's vehicles and opened fire, striking two passengers, police said in a news release.

Both victims were transported to Loyola Medical Center, where one is in critical condition and the other is in critical but stable condition, according to police.

Two passengers in a second vehicle within the procession were also shot and were treated for non-life-threatening injuries at a local hospital.

"Multiple shell casings were recovered at the scene but no bystanders were injured in the shooting," police said in the release.

Saturday's shooting is among 288 mass shootings so far in 2023, according to the Gun Violence Archive, which defines a mass shooting as one in which four or more people are injured or killed, not including the shooter.

A father and son inside a music school near where the shooting occurred initially mistook the sound of gunshots for a musical instrument, according to CNN affiliate WLS-TV.

"We were talking to the person at my kid's music lesson, and all of a sudden, we heard what sounded like a snare drum," Jaime Rava told WLS-TV. "It was like a rhythmic sound, and (the instructor) was like, 'We don't have any drum lessons scheduled for today.'"

Authorities said there was no threat to public safety as they continued investigating the shooting.

"While there is no indication of any further threat to the community stemming from this incident, any act of gun violence such as this does great harm to our collective sense of safety," Oak Park Police Chief Shatonya Johnson said in a statement.

Standard protocol for funeral homes is to alert law enforcement agencies along routes of potentially high-risk funeral processions so officers can assist with traffic flow and public safety, the police news release stated.

Police said no such alert was provided leading up to Saturday's procession.

Authorities have asked anyone with information about the shooting to contact the Oak Park Police Department.