The suspect who police believe gunned down two firefighters Sunday after starting a brush fire in Idaho wanted to pursue a career as a firefighter himself, his grandfather told CNN.

New details are emerging about the 20-year-old suspect that police say started a brush fire and then began shooting at firefighters responding to it in an ambush-style attack. Police say he has no criminal record and likely used a shotgun before dying from a self-inflicted wound six hours after the shooting began.