Driver arrested after high-speed chase through central Montana By: MTN News and last updated 2020-12-10 12:57:02-05 GREAT FALLS â A person was arrested after leading law enforcement officials on a high-speed chase through three central Montana counties on Wednesday, running several vehicles off the road. Musselshell County Sheriff Shawn Lesnik said in a news release that the chase started at 2:11 p.m. on US Highway 87 North just north of Roundup. The chase initially involved the Montana Highway Patrol and Musselshell County Sheriff's Office, and then deputies from Petroleum and Fergus counties joined at Grass Range, according to Lesnik. The driver ran several southbound vehicles off the road during the chase.