MISSOULA, Mont. -

Investigators believe they know what caused a highway crash that killed six people last month, but their findings are under review before they can be released.
    
The Montana Highway Patrol investigation has lasted for weeks as authorities attempted to piece together what happened in the June 19 collision between a fire engine and a pickup truck.
    
The crash and fire on U.S. Highway 12 outside Helena killed Three Forks Fire Chief Todd Rummel and a couple and their three young children. There were no survivors.
    
Department of Justice spokesman John Barnes said Monday investigators have forwarded their findings to a team of crash re-constructionists, who will review them for thoroughness and accuracy.
    
Details of the findings were not released.