Security door and security area

A security door comprising:

• a frame structure having a lateral surface in which a plurality of doorways is constructed, wherein a first doorway constructed in the lateral surface of the frame structure has a first width along an inner circumference of the frame structure, and wherein lateral surface portions delimiting the first doorway in a first direction and in a second direction along the inner circumference of the frame structure have a second width, wherein the second direction opposes the first direction, and
• a lock element received in the frame structure,
• the lock element comprising a first segment, which is movable along the inner circumference of the frame structure relative to the frame structure, and a second segment, wherein said second segment is movable independently of the first segment along the inner circumference of the frame structure relative to the frame structure, and wherein said second segment is movable to a position in which an end surface of the second segment directly contacts an end surface of the first segment,
• wherein the first segment of the lock element is dimensioned so that, in a position in which the first segment closes the first doorway, the first segment also closes a second doorway adjacent to the first doorway in the first direction along the inner circumference of the frame structure.