A person of interest in the mass killing that targeted a Fourth of July parade in the Chicago suburb of Highland Park has been taken into custody, the Highland Park police chief said on Monday evening.

More than 100 law enforcement officers had scoured the suburb and surrounding areas after at least six people were killed when a lone gunman rained down bullets on the town’s independence celebrations on Monday morning.

Thirty people were injured in the attack, with ages ranging from eight to 85, said Dr Brigham Temple, medical director of emergency preparedness at NorthShore University health center where 26 of the injured were treated. At least four of the injured are believed to be children.