Police have found the getaway car of a US military veteran who walked into a bar in the western state of Montana on Friday morning and fatally shot four people, but the gunman remains at large.

Blake Hempstead, a local sports reporter in the area, posted on X, "Anaconda is in a mini lock down while police search for a gunman who shot numerous people at the Owl Bar. Don't leave your house or come this way until this cowardly POS is found by our law enforcement officers."