A door security system is provided which is used to prevent a door, which separates first and second spaces, from opening. The door security system includes a security apparatus which is configured to be engaged with the floor within a first space. If the door is to be opened into the first space, the security apparatus blocks the door from opening into the first space. If the door is to be opened into the second space, an attachment assembly of the door security system acts in concert with the attachment assembly to block the door from opening into the second space. The door security system further includes a release mechanism which can be manipulated from the second space to disengage the security apparatus within the first space, thereby allowing for the door to be opened into either the first or second spaces, as appropriate.