A well being drilled in a zone previously under pressured and depleted took a kick and caught on fire. The drilling crew was stopped to take a MWD survey when the driller noted an increase in his pit level along with an increase in background gas. The driller called the company man on location and informed him, waited a minute more and called him again to point out the situation had gotten worse. After receiving no orders during the second call, he went to the drawworks controls and started to pick up the Kelly and close in the well. During this procedure the well unloaded and exploded, catching the back of the Driller on fire as he raced to the BOP Remote. The Driller with the help of another employee in the doghouse rolled on the floor and extinguished the fire on his back. He then exited the doghouse. The Rig Manager attempted to gain control of the well but was unsuccessful. The results were a burn to the back area of one employee and the total loss of a drilling rig.