Ascon Oil released this statement of their
official Facebook page. Read below...
Ascon Oil Fire Outbreak: No Life Lost. Fire
Contained
The fire incident at Ascon Oil filling station at
Lekki Phase 1 this afternoon has been
contained. Contrary to earlier speculations,
the main building and the reservoirs are
unaffected. The incident emanated from a
discharge at the point of offloading product
from a tanker, engulfing two tankers and
some vehicles parked by the road side.
It was an accident compounded by the current
fuel scarcity in the country with ASCON OIL
being one of the few stations with a reliable
steady supply even in times of scarcity. No life
was lost to the incident, the pumps are intact
and emergency fire service officers were
already on site containing the flames as at
the time of this report.
ASCON OIL wishes to reaffirm its commitment
to serving its customers even in the face of
accidents of this nature for which a company
of its pedigree is always prepared. Residents
and passers-by showed solidarity with the
company as they contributed in no small way to
contain the flames.

Source: Linda Ikeji blog

Static electricity could be a source of ignition in such operation.
Proper investigation will identify the immediate and root causes of the accident...
This accident could have been prevented if ignition sources were controlled during the discharging operation.
- Access control around the immediate area
- Prohibit smoking and naked flames
- Prohibit the use of mobile phones and portable electrical equipments until operation is completed.
- Ensure that the vehicles /discharge hoses are properly grounded to dissipate static charges.
- Use conductive hoses for the operation.
Control flow rates and fill Heights.... Higher flow rates increase the build up of static electricity.
- Use pumps that are fitted with spark arrestor and ensure they are positioned upwind and at reasonable distance (15m) from the discharge point.
- Continually monitor the environmental conditions for signs of lightning... High humidity is preferable
- Properly position fire fighting equipments such as extinguishers...

Just my opinion