Why is my amp shutting off?

I have a 1200 wat power acoustik BAMF 2 channel amp with a 2 ohm load run with 4 guage wire and grounded to the chasie. the amp is powering (2) 10 inch sony xplod speakers with 1100 wats each ( prolly bout 350 RMS each) i have the two speakers bridged to one channel and after about 20 min of play my amp is shutting off. the amp is in the trunk of my 2000 honda civic and usually leave the back seat down to let airflow into the trunk but still no help if anyone could help me out with this maybe anything that i should change it would be much apreciated... oh and i also am only running the amp at 50% gain and it still shuts off