It's good to think about this problem before it's needed.
My thought is to make up movable "panels", made of a square (48") of 3/4" plywood. Imagine the first square, then framed with 2 X 3's around the perimeter, topped off with the second piece, like a shallow box. Stands upright and is filled with sand. Would be placed in the likely lanes of fire. I choose 2 X 3's because using 2 X 4's make a bigger box with much more sand in between. Probably would weigh about 300 - 350 pounds. In combination with other objects in the room the panel should provide suitable protection.
It's funny, I've been thinking about this need and now it turns up on the forum.