Door security system and method of using same

In combination with a vertical door that opens from a second space into a first space, the second space connected to the first space by a floor extending underneath the door, a door security system comprising:

• a multi-angled door blocking plate comprising a substantially flat main body having an inner face and an outer face, an inwardly-angled top portion at an upper end of the main body extending at an angle over the inner face, and a pair of spaced pins extending downwardly from a lower edge of the main body parallel to the main body;
• a pair of holes formed in the floor in the first space adjacent an inner side of the door, the pair of holes spaced corresponding to a spacing of the spaced pins on the door blocking plate;
• the inwardly-angled top portion including a handle;
• wherein,
• the door blocking plate is operatively engageable with the inner face of the door to prevent the door from being opened into the first space by inserting the spaced pins in the spaced holes in the floor such that the outer face of the main body of the door blocking plate is located adjacent and facing the inner face of the door and the inwardly-angled top portion of the door blocking plate is angled away from the door into the first space.