Parts of a national forest near Anaconda, Montana, were closed late Saturday as authorities expanded their search for the gunman accused of killing four people at a bar on Friday morning.

Authorities say a former US soldier suspected of killing four people at a Montana bar is still at large and believed to be armed.

Military veteran Michael Paul Brown, 45, is suspected of carrying out a shooting at a Montaba bar that left four people dead. A manhunt is currently underway, with Brown still to be caught as authorities search for him across a mountainous area.