please help me!!!

first of all im gonna let you know how everything was set up.
I have 3 amps including the one that surged, a mtx thunder 250x powering the front speakers, a sony xm1002hx powering the rear speakers and the lanzar mxa232 powering the subs....i have mtx thunder6000 12"s rated at 250rms/500peak @4ohms single i hooked up my system, i did the big3 with 4awg wire and a fuse holder cuz i didnt have 1awg. i did my pwr connection with a fuse holder to a 4awg to 8ga distribution block with fuses....and from there to the amps with 8gauge wire....
the ground wire was 8ga up to the lanzar(1000watts peak) and from this one a 4ga to the chasis...i ran my system and everything was ok, the pound was decent and there was no head light dimming at worked fine for about 30 mins, i went to walmart and when i got back the subs werent working, so i looked at the 30A fuse in the lanzar and it was done....with the car turned off i tried putting a new fuse and it sparked, so i tried again and thats when smoke came out of my amp....i disconnected the batt+ and put another fuse...the amp worked again but i had to lower the bass because it was getting too hot and smoke was coming out i went home and when i left again and put the music the smell came again, i turned off the music and took out the fuse that corresponds to the lanzar in the distribution block....i know i was told to get a 4ga to 4ga dist block but this is all i had....i also didnt use a bottle(1farad cap) or anything....what could have cost this to happen and wat can i do to prevent it next time i get another amp for the subs(most likely same amp/warranty) the way the other amps are still good... i need help please....thanks
here are the pics that show the burning....<>