A mobile apparatus provides a safe environment for controlling oil wellhead gushers and fires at such gushers. It includes a main compartment, having a gas exchange lock access, and a flue stack, having a flue outlet, which form a gastight enclosure at the area around the wellhead. The flue stack opens to atmosphere at the flue outlet and a portion of the flue stack is moveable to control the size of the opening and, thus, the flow rate of exiting gases. A nonflammable environment is established in the apparatus, any fire present at the wellhead is relocated exterior to the enclosure, and the relocated fire is extinguished. The apparatus can be provided with at least one baffle that temporarily retains liquids impinging on it while not preventing the flow of gases from the enclosure, and a recovery basin that is positioned below the liquid-gas separation baffle(s) so as to collect and pass the liquids so collected exterior to the apparatus for recovery.