A placard used to mark abandoned or unsafe buildings for firefighters.
This warns of significant dangers inside of the building, firefighters should only attempt to fight any fire from the outside of the structure. Entry should only be made to save human lives.

(This is SVG is reduced in scale by 50% from the standard measurements, 24 inches by 24 inches (610mm by 610mm).
Drawn in Adobe Illustrator, following standards laid out in 311.5 Placards.
User:The Navigators

International Fire Code, via the International Code Council.