Duluth, MN (KDAL) - Authorities are investigating after a rifle exploded and injured two men north of Duluth. The Saint Louis County Sheriff’s Office says the incident happened Sunday afternoon at the United Northern Sportsman firing range off of Rice Lake Road in Gnesen Township, near Island Lake. According to investigators, 34 year-old John Kubiak of Duluth was firing a bolt action rifle when it blew up just after 2:00. The force of the blast sent the bolt out of the back of the rifle and into the chest of 61 year-old David Shrader of Duluth, who was standing behind Kubiak at the time. Neither Kubiak or Shrader were seriously hurt, though Kubiak, whose thumb was severely injured in the explosion, was later treated at St. Mary’s/Essentia. Why the rifle blew up in the first place isn’t known.