Latest information from local newspaper and conversation with a United/Continental mechanic supervisor was that there was no actual fire, only an "avionics smoke warning message". The flight crew began a shutdown of all non-essential equipment per emergency procedures. Also the on-board computers on the A320 automatically shut down some avionics and control functions which resulted in loss of control and blown tires on landing(no antiskid braking).
My source at KMSY says he does not like Airbus Fly By Wire because of just this scenario. In an emergency, or indication of an emergency, the computer(s) shut down systems without pilot input and the pilot has no instant override.
This was not as serious as it sounded, but was still no piece of cake, with systems shut down, IFR to marginal VFR, overweight landing, short runway and loss of steering control. Also runway 19 ends just short of a major US highway(61) which was loaded with traffic at that hour. A runway overrun would have been a major disaster.