A Danity Kane recording sesh erupted in violence Monday.

We're told bandmates Dawn Richards and Aubrey O'Day got physical during a disagreement at an L.A. studio on Monday, resulting in Dawn slugging Aubrey in the head with a closed fist.

DK's third member, Shannon Bex, was also there and tried unsuccessfully to break up the fight. This isn't the first time DK's had issues ...

Aubrey filed a battery report. Cops are investigating.

Source: TMZ