Select an interior room in your home with no windows or exterior entry.
Install reinforced steel security bars on the inside of the door. Use the manufacturer's instructions for installation, but ensure they are secured to the studs in the walls when installed.
Fit pre-fabricated steel wall panels to the room, if your budget allows. The room must be measured and the steel panels made to order.
Add key-only entry dead bolt locks to the door. Key only means the locks do not manually open but a key must be used for entry and exit. One is generally sufficient, but for a high security room, a double lock system is recommended.
Place an emergency, battery-powered light system in the room. Have a secondary supply of batteries available for the lights.
Provide sanitation supplies such as a portable, bucket-type elimination system for bodily fluids, and cleaning supplies. Add in emergency food and water, in case the shelter will be used for an extended period of time. A three-day supply is sufficient, as this type of shelter is not meant to be used long term.