VIDEO: Officials with the Milwaukee Fire Department on Monday, Sept. 10 explained the controversial vacant structure placarding program to Milwaukee Common Council members after some aldermen expressed concerns. MFD officials told FOX6 News the placards are posted to help keep firefighters safe. A sign with one slash indicates the building is compromised and crews should enter with caution. The placards with an "X" signify the building is unsafe to enter unless there is a known life safety hazard in a known location. Some aldermen said they weren't notified about this effort. "It really is what's best for our firefighters," said MFD Chief Mark Rohlfing.