Please, please, please. If you find a building has been broken into, take immediate action to have the building secured. Contact the owner, the city police, and the building inspection department. Every moment that a building remains accessible is another moment for theft, vandalism, exposure to the elements, and possibly a fire.
The Salvation Army Building is a prime example of how a building went from being an active enterprise to a candidate for demolition within two years. It started when someone broke into the building. Within a short period of time, everying of value, including the windows and doors, was stripped out.