I had to call a friend in Calabar to get the spot gist on this Calabar explosion, and he told me that they news is that a Welding operation to place and gas cylinder explode.
The only link between heavy wielding and cutting activity is the use of Oxy acetylene for the operation.

The danger of Storing Acetylene Tanks on their side with flashback is always an EXPLOSION

A portable oxygen cutting and welding outfit. ACETYLENE is a flammable fuel gas composed of carbon and hydrogen having the chemical formula C2H2.
When burned with oxygen, acetylene produces a hot flame, having a temperature between 5700°F and 6300°F. Acetylene is a colorless gas, having a disagree- able odor that is readily detected even when the gas is highly diluted with air. When a portable welding outfit, similar to the one shown in figure 4-3 is used, acetylene is obtained directly from the cylinder. In the case of stationary equipment, similar to the acetylene cylinder bank shown in figure 4-4, the acetylene can be piped to a number of individual cutting stations. Hazards Pure acetylene is self-explosive if stored in the free state under a pressure of 29.4 pounds per square inch (psi). A slight shock is likely to cause it to explode.

WARNING Acetylene becomes extremely dangerous if used above 15 pounds pressure. Figure 4-4.—Stationary acetylene cylinder bank.

Cylinder Design Acetylene can be safely compressed up to 275 psi when dissolved in acetone and stored in specially de- signed cylinders filled with porous material, such as balsa wood, charcoal, finely shredded asbestos, corn pith, portland cement, or infusorial earth. These porous filler materials aid in the prevention of high-pressure gas pockets forming in the cylinder. Acetone is a liquid chemical that dissolves large portions of acetylene under pressure without changing the nature of the gas. Being a liquid, acetone can be drawn from an acetylene cylinder when it is not upright.
You should not store acetylene cylinders on their side, but if they are, you must let the cylinder stand upright for a minimum of 2 hours before using. This allows the acetone to settle to the bottom of the cylinder.
NOTE: Acetone contaminates the hoses, regula- tors, torch, and disrupts the flame. Acetylene is measured in cubic feet. The most com- mon cylinder sizes are 130-, 290-, and 330-cubic-foot capacity. The standard size cylinder the Navy uses holds 4-3

Pictures are the result of an explosion involving an Acetylene /Oxygen rig stored inside a van. Ignition source was a remote keyless entry. Acetylene has one of the widest explosive ranges of the flammable gases.

Note this is completely my view, we hope the relevant agencies will come with a comprehensive report on this incident.

Hmmm.. ok