The suspect accused of fatally shooting four people at a Montana bar, who remains at large, struggled with mental health issues but was denied services from agencies that were supposed to help, according to his niece.

The mental health of suspected Montana gunman Michael Paul Brown, 45, declined significantly following the death of his mother, relatives said.

A manhunt is intensifying for the gunman who allegedly killed a bartender and three patrons at a bar in southwestern Montana, authorities said.