Rollover: Rollover is defined, as sporadic flashes of flame mixed with smoke at ceiling level. Rollover is caused by heated combustible gases in smoke, which ignites into flashes of flame when mixed with oxygen in the air. Rollover precedes flashover. Rollover is another warning sign of flashover, which may be seen in the smoke coming out of the tops of doorways or window openings of burning rooms before flashover occurs. When searching for the location of a fire and there is no discernible heat in the smoke or signs of rollover, firefighters may enter and proceed for some distance into a fire area. However, If one of these warning signs is discovered and a flashover danger exists, defensive search procedures must be used by firefighters. Standard tactics and procedures must be curtailed and defensive search and rescue procedures substituted when there is a danger of flashover.