Safety blinds for installation in an opening in a building such as a door or window includes a closure covering the opening, a plurality of projections along the side edges of the opening and a plurality of corresponding apertures along the side edges of the closure, whereby locking the projections into the openings prevents the closure from opening and also prevents the side edges of the closure from being displaced from the side edges of the opening. In another embodiment, the projections from the closure cooperate with a continuous channel along the edge of the opening whereby the projections can move within the channel for opening and closing the closure and can be locked in position for again preventing the closure from being opened.