(CNN) Four people were shot and injured while attending "a large planned event with several hundred people in an open field," in St. Louis late Saturday night, police said.

Around 11:43 p.m., officers from the North County Precinct responded to a call for service involving shots fired, according to a news release from the St. Louis County Police Department.

When officers arrived, they found four gunshot victims who were all transported to area hospitals, one with a life threatening injury. The remaining three have injuries that are not life-threatening, police said.

According to police, it appears that during the event a disturbance broke out between several individuals leading to the shots being fired and it does not appear to be a random shooting.

The investigation is "very active" at this time and being led by the St. Louis County Police Department's Bureau of Crimes Against Persons, according to the department's release.