Here's a lightweight bout between Nathias Frederick and Ahmad Aswad in the Fight UK MMA - Last Man Standing, whatever that is. Skip to 6:20 in the video above for the incident in question.
With 40 seconds to go in the fight, Frederick floors Aswad and follows in with a close-range flurry, because battering your opponent after you knock him down is totally fine, apparently. Totally fine that is, until the referee sees enough of your wanton brutality and decides to clear you out before going to check on the beaten fighter. Great stuff.
On the subject of refs getting involved in the action, here's Howard Webb taking a tumble during Ledley King's testimonial last night.