More than 1,000 Birmingham supporters invaded the pitch after their side's 2-1 win at St Andrew's and confronted the 3,800 Villa fans situated in the Gil Merrick Stand at the other end of the stadium.
A flare appeared to be thrown into the section housing the Villa supporters although it was then tossed backwards and forwards between the rival factions. Seats were also ripped out and used as missiles along with other objects.
The FA on Friday described the incidents as "serious crowd disturbances" and have given Birmingham until next Friday, March 11, to respond.
Birmingham said in a statement they "would like to thank the FA for their assistance and communication prior to and during the investigation".
Source: PA
