All buildings of three and not exceeding four stories in height hereafter erected or altered, in this state, which are used, or intended to be used for any of the purposes mentioned in sections 320.010 to 320.060, shall be provided with exterior stationary stair or tubular fire escapes, or at the option of the owner may be provided with interior fireproof fire escapes, and all such buildings, exceeding four stories in height shall be provided with interior fireproof fire escapes. All interior fire escapes shall be installed in fireproof shafts constructed of brick or concrete, and shall extend from the ground to the top of the building, with an exterior entrance thereto at each story and shall have no openings of any kind leading to or from the interior of the building. The doors on the ground floor of every such shaft shall open directly into a street, alley, yard, or outer court or directly into an enclosed fireproof corridor or passageway, constructed of brick or concrete, and leading directly to and opening into a street, alley, yard or outer court. All buildings coming within the provisions of this section, and not exceeding four stories in height, shall be provided with such a number of exterior stationary stair or tubular fire escapes as are required by section 320.030; provided, that number are so located that no part of the floor area of any floor above the first story will be more than one hundred feet distant from a fire escape, or if such building be provided with interior fire escapes, there shall be one for every two hundred persons or fractional part thereof for whom working, sleeping or living accommodations are provided for above the second story. There shall be a sufficient number of fire escapes so located that no part of any floor space above the first story will be more than one hundred feet from a fire escape, whether they are interior or exterior fire escapes.