Crews also called in water tankers to help them fight the fire at 27400 Lougheed Highway.
it's the second time in a year, there has been a weekend fire at the mill.
In Dec 2013, a fire sparked by a welder's torch ignited a major blaze that also required water tankers and the assistance of the Mission fire department.
In that case the fire was contained to the building that housed the chipper unit.
The extent of the damage to the shake and shingle mill from Saturday's fire is unknown but is being assessed today.
Fire investigators are also on scene today trying to determine the cause of the blaze.
It's not known how seriously the fire may have affected production.