The incident occurred during a protest outside Ferguson police headquarters and comes less than 24 hours after the resignation of the city's chief of police.
The St. Louis Post-Dispatch reports two police officers have been shot outside the Ferguson Police Department. The extent of any injuries isn't known.
FEMA's move comes after months of questions about whether insurance companies shortchanged homeowners.
An assistant chief will replace Tom Jackson; a Justice Department probe following the shooting death of Michael Brown had found serious problems in how the department operated.
The cause was complications of ALS. He is survived by his husband, Wash Westmoreland, who co-wrote and co-directed Still Alice. They are also known for their 2006 film Quinceanera.