Sparks from loose mechanical parts triggered Monday's huge explosion in Wong Tai Sin after petrol vapours reached saturation point inside a cargo container carrying 159 used motorcycles, police said yesterday.
'There was no ventilation inside the container. All it took was a spark for the petrol vapours to go off,' a police district spokesman said.
The news came as senior transport and fire services officials held an emergency meeting yesterday to discuss the explosion and look into ways to prevent similar accidents.
Both departments admitted the accident fell outside the Dangerous Goods Ordinance and various traffic regulations governing cargo transport.
Three people nearby were slightly hurt when the explosion ripped open the top of the container in Lung Cheung Road and sprayed motorcycle debris up to 120 metres into the air.
The blast overturned another truck travelling in the opposite direction.